I
`
`I
`I
`
`i I
`I
`I
`
`·,·
`
`San Francisco
`New York Chicago
`Lisbon London Madrid Mexico City
`Milan New Delhi
`San Juan
`Seoul
`Singapore Sydney Toronto
`
`1
`
`IS 1012
`
`

`

`On the cover: Representation of a fullerene molecule with a noble gas atom trapped
`inside. At the Permian-Triassic sedimentary boundary the noble gases helium and argon
`have been found trapped inside fullerenes. They exhibit isotope ratios quite similar to
`those found in meterorites, suggesting that a fireball meteorite or asteroid exploded
`when it hit the Earth, causing major changes in the environment. {Image copyright ©
`Dr. Luann Secker. Reproduced with permission.)
`
`Over the six editions of the Dictionary, material has been drawn from the following references: G. M. Garrity
`et al., Taxonomic Outline of the Proca,yotes, Release 2, Springer-Verlag, January 2002; D. W. Linzey, Vertebrate
`Biology, McGraw-Hill, 2001; J. A. Pechenik, Biology of the Invertebrates, 4th ed., McGraw-Hill, 2000; U.S.
`Air Force Glossary of Standardized Terms, AF Manual 11-1, vol. 1, 1972; F. Casey, ed., Compilation a/Terms
`in Information Sciences Technology, Federal Council for Science and Technology, 1970; Communications(cid:173)
`Electronics Terminology, AF Manual 11-1, vol. 3, 1970; P. W. Thrush, comp. and ed., A Dictionary of Mining,
`lvlineral, and Related Terms, Bureau of Mines, 1968; A DOD Glossa,y of Mapping, Charting and Geodetic
`Terms, Department of Defense, 1967; J. M. Gilliland, Solar-Terrestrial Physics: A Glossa,y of Terms and
`Abbreviations, Royal Aircraft Establishment Technical Report 67158, 1967; W. H. Allen, ed., Dictionary of
`Technical Terms for Aerospace Use, National Aeronautics and Space Administration, 1965; Glossary of Stinfo
`Terminology, Office of Aerospace Research, U.S. Air Force, 1963; Naval Dictionary of Electronic, Technical,
`and Imperative Terms, Bureau of Naval Personnel, 1962; R. E. Huschke, Glossa,y of Meteorology, American
`Meteorological Society, 1959; ADP Glossa,y, Department of the Navy, NAVSO P-3097; Glossary of Air Traffic
`Control Terms, Federal Aviation Agency; A Glossary of Range Terminology, White Sands Missile Range, New
`Mexico, National Bureau of Standards, AD 467-424; Nuclear Terms: A Glossa,y, 2d ed., Atomic Energy
`Commission.
`
`McGRAW-HILL DICTIONARY OF SCIENTIFIC: AND TECHNICAL YER.MS,
`Sixth Edition
`Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by The McGraw-Hill Companies, Inc. All rights
`reserved. Printed in the United States of America. Except as permitted under the United States Copyright Act
`of I 976, no part of this publication may be reproduced or distributed in any form or by any means, or stored
`in a database or retrieval system, without the prior written permission of the publisher.
`
`234567890
`
`DOW/DOW
`
`0876543
`
`ISBN 0-07-042313-X
`
`Library of Congress Cataloging-in-Publication Data
`
`McGraw-Hill dictionary of scientific and technical te1ms--6th ed.
`cm.
`p.
`ISBN 0-07-042313-X (alk. paper)
`I. Science--Dictionaries. 2. Technology--Dictionaiies.
`and technical terms.
`
`I. Title: Dictionary of scientific
`
`Ql23.M15
`503-dc21
`
`2002
`
`2002026436
`
`2
`
`

`

`148
`
`aspiration psychrometer
`
`assembly system
`
`[ENG] A psychrometer in which
`aspiration psychrometer
`the ventilation is provided by a suction fan.
`{ ,as·pa'ra·shan
`,si'kriim·;id•;ir ]
`[ENG] A thermograph in which
`aspiration thermograph
`{ ,as•p;i'ra·sh;in
`ventilation is provided by a suction fan.
`1thclrm•g 1graf }
`aspirator
`[ENG) Any instrument or apparatus that utilizes a
`vacuum to draw up gases or granular materials.
`[MIN ENG]
`A device made of wire gauze, of cloth, or of a fibrous mass
`held between pieces of meshed material and used to cover the
`mouth and nose to keep dusts from entering the lungs. { 'as·
`p;i,rad•;,r }
`aspirin See acctylsalicylie acid.
`{ 'as·pran ]
`aspite
`[GEOL] A cratered volcano with the base wide in
`relation to the height; for ernmplc, Mauna Loa.
`{ 'as,plt ]
`asporogenic mutant
`[MICROBJO] A bacillus that is unable
`to form spores due to alterations at any of several gene loci.
`{ :a,sp6r•;,~en·ik 'myiit•;,nt ]
`asporogenous
`[BOT] Not producing spores, especially of
`certain yeasts.
`{ :rr·spa'raj·a•n;is ]
`[VERT zoo] A family of salt-water catfishes
`Aspredinidae
`in the order Siluriformes found off the coast of South America.
`{ ,a·sprn'clin·;i•dc]
`ASROC See antisubmarine rocket.
`{ 'as,rlik ]
`[VERT zoo] Any of several perissodactyl mammals in
`ass
`the family Equidae belonging to the genus Equus, especially
`E. hemio11us and E. asinus.
`{ as ]
`assault
`[Olm] 1. Final phase of an attack; closing with the
`enemy in hand-to-hand fighting. 2. The landing or troops for
`attack on the enemy's beach defenses. 3. The landing of
`parachute and glider elements on unsecured and unprepared
`drop zones and landing zones to attack and seize an airhead.
`4. A short, violent, but well-ordered attack against a local
`objective, such as a gun emplacement, fort, or machine gun
`nest.
`( ;i's6lt }
`assault aircraft
`[AERO ENG] Powered aircrnrt. including
`helicopters, which move assault troops and cargo into an objec(cid:173)
`{ :,'s61t
`tive area and which provide for their resupply.
`'er,kraft ]
`assault boat
`[NJ\V ARCH] A small boat that can easily be
`transported on land; used for amphibians military attacks or to
`cross lakes and rivers in land warfare.
`{ a's61t ,bot ]
`[ORD] 1. Fire delivered by attacking troops as
`assault fire
`they close with an enemy to engage him at close range or in
`hand-to-hand fighting, usually delivered from the hip or the
`standing position at a sustained rate. Also known as advancing
`fire. 2. In artillery, extremely accurate, short-range destruc(cid:173)
`{ a's6lt ,fir }
`tion fire at point targets.
`assault gun
`[ORD] Any of various sizes and types of guns
`that arc self-propelled or mounted on tanks and are used for
`direct fire from close range against point targets.
`{ a's6lt
`lg:~m}
`assault-landing model
`[ ORD] A special form of assault
`model designed specifically for planning amphibious landings.
`( a's61t
`Also known as amphibious-assault landing model.
`:1und·i1J ,mM·:il ]
`assault model
`[ORD) Vehicle designed to provide direct fire
`in combat.
`{ ;i's6lt ,miid·:il ]
`assay
`[AN ALY CHEM] Qualitative or quantitative determina(cid:173)
`tion of U1e components of a material, as an ore or a drug.
`! 'a,srr]
`,
`assay balance
`[ENG]
`assaying of gold, silver,
`,bal•;ins]
`assay bar
`[MET) A bar of pure or nearly pum gold and
`silver; used by a government as a standard.
`{ 1a,sU 1bii.r }
`assay plan
`/\ mine map showing the assay, slope,
`[MIN ENG)
`width, and so forth of samples taken from positions marked.
`1(cid:143)
`1sa 1plan }
`assay pound
`[MIN ENG] A weight which varies from time
`to time but is sometimes 0.5 gram, and is used by assayers to
`proportionately represent a pound.
`{ 'a,sa ,paimd ]
`assay ton
`[MIN ENG] A unit of weight ofore equal to 29,167
`milligrams; the number of milligrams of precious metal in this
`measure equals the number of troy ounces in a short ton.
`1a 1sa 1t~m J
`assay value
`[MIN ENG] The amount of gold or silver as
`shown by assay of any given sample and represented by ounces
`{ 'a,sa ,val·yU ]
`per ton of ore.
`
`{
`
`{
`
`{ a'sem·blar
`
`assay walls
`[MIN ENG] The planes to which an ore body
`can be profitably mined, the limiting factor being the metal
`content of the coul'i,1)' rock as determined from assays.
`{ 'a,sa ,w6lz}
`[ARCHEO] All related cultural traits and arti(cid:173)
`assemblage
`facts associated with one archeological manifestation.
`[ECOL]
`A group of organisms sharing a common habitat b~ chance.
`[ GEOL] 1. A group of fossils that, bppearing togethet, charac(cid:173)
`terize a particular stratum. 2. A gr~up of minerals that com(cid:173)
`pose a rock.
`[ORD] A collection of items designed to
`accomplish one general function aird identified and issued as
`Iii. group of fossils occuning
`a single item.
`[PALEON]
`together at one stratigraphic level.
`{ :,'sem ·blij ]
`[PALEON] A biotstratigraphic
`assemblage zone
`unit
`defined and identified by a group of associated fossils rather
`than by a single index fossil.
`( a'sem·blij ,zon }
`assembled stone
`[MATER] A stone made of two or more
`gem matelials, whether genuine or imitation.
`{ a'sem·b;ild
`'ston )
`assembler
`[COMPUT SCI] A program designed to convert
`symbolic instruction into a form suitable for execution on a
`computer. Also known as assembly program; assembly rou(cid:173)
`tine.
`{ a'scm·bl;;ir }
`assembler directive
`in an
`[COMPUT SCI] A statement
`assembly-language program that gives instructions to
`the
`assembler and does not generate machine language. { ;:i'sem·
`bl;ir di,rek·tiv ]
`assembler language See assembly language.
`,lal)·gwij]
`assembler program
`[COMPUT SCI) A program that is writ(cid:173)
`{ a'scm·blar ,pro·gram]
`ten in assembly language.
`assembling bolt
`[CIV ENG) A threaded bolt for holding
`together temporarily the several parts of a structure dming
`riveting.
`{ ;;,'sem·bli1.1 ,bolt]
`assembly
`[ COMPUT sct] The automatic
`into
`translation
`machine language of a computer program written in symbolic
`[MECH ENG) A unit containing the component
`language.
`parts of a mechanism, machine, or similar device. { ~1sem·
`b!c l
`assembly drawing
`[GRAPHICS] A working-type
`engi(cid:173)
`neering drawing depicting a complete unit, usually included
`with detail drawings of all parts in a set of working drawings.
`( a'sem·ble ,dr6·i1J }
`assembly language
`[COMPUT SCI] A symbolic, nonbinary
`formal for instructions (human-readable version of machine
`language) that allows mnemonic names to be used for instruc(cid:173)
`tions and data; for example, tl1e instruction to add the number
`39321 to the contents of register DI in the central processing
`unit might be written as ADD#39321, D1 in assembly language,
`as opposed to a string of O's and I's in machine language.
`{ ;i'sem·blc ,laIJ·gwij ]
`assembly line
`[!ND ENG) A mass-production arrangement
`whereby the work in process is progressively transferred from
`one operation to the next until the product is assembled.
`{ :'.l'sem·ble ,lin ]
`assembly-line balancing
`[IND ENG) Assigning numbers of
`operators or machines to each operation of an assembly line
`so as to meet the required production rate with a minimum of
`idle time.
`{ ;i'sem·ble ,lrn 'bal·ans·iIJ }
`assembly list
`[COMPUT SCI) A printed list which is the by(cid:173)
`product of an assembly procedure; it lists in logical instrnction
`sequence all details of a routine, showing the coded and sym(cid:173)
`bolic notation next to the actual notations established by the
`assembly procedure; this listing is highly useful in the debug(cid:173)
`ging or a routine.
`{ a'sem·ble ,list }
`assembly machine
`[MECH ENG) A machine in a manufac(cid:173)
`turing facility that produces a configuration of some practical
`value from discrete components. { ;i'sern·ble ma,shen }
`assembly method
`[IND ENG) The technique used to assem(cid:173)
`ble a manufactured product, such as hand assembly, progressive
`line assembly, and automatic assembly.
`{ a'sem·ble ,meth·
`;id l
`assembly program See assembler.
`[ ;i'sem·ble 'pro·gr;im }
`assembly robot
`[COMPUTSCI] A robot that positions, mates,
`fits, and assembles components oi• parts and adjusts the finished
`{ a'sem·ble ,ro,biit]
`product to function as intended.
`assembly routine See assembler.
`{ ;i'sem·ble ril'ten ]
`assembly system
`[COMPUT SCI) An automatic pi"ogram(cid:173)
`ming software system with a programming language and
`
`A sensitive balance used
`and other precious metals.
`
`the
`in
`{ 'a,sa
`
`3
`
`

`

`assembly time
`
`associative memory
`
`149
`
`machine-language programs that aid the programmer by per(cid:173)
`forming different functions such as checkout and updating.
`{ a'sem·ble ,sis·t;,im )
`assembly time
`[ ENG) 1. The elapsed time after the applica(cid:173)
`tion of an adhesive until its strength becomes effective. 2.
`The time elapsed in performing an assembly or subassembly
`operation. { a'sem·ble ,tTm )
`assembly unit
`[coMPUT SCl) 1. A device which performs
`the function of associating and joining several parts or piecing
`together a program. 2. A portion of a program which is capa(cid:173)
`ble of being assembled into a larger program. { ;i'sem·ble
`,yii·n:it)
`assessment drilling
`the
`fulfill
`to
`[MIN ENG] Ddlling
`requirement that a prcscdbed amount of work be done annually
`on an unpatented mining claim to retain title. Also known as
`annual labor.
`{ ;i'ses·mant ,dril·iIJ }
`assessment work
`[MIN ENG) Annual work at an unpatented
`mining claim in the public domain performed under law to
`maintain the claim title. { ;i'ses·mant , wark }
`assets
`[IND ENG) All the resources, rights, and property
`owned by a person or a company; the book value of these items
`as shown on the balance sheet. { 'a,sets }
`assign
`[COMPUT SCI] A control statement in FORTRAN
`which assigns a computed value i to a variable k, the latter
`representing the number of the statement to which control is
`then transferred. { :i 'sin }
`assignable cause
`[IND ENG] Any identifiable factor which
`causes vanat10n in a process outside the predicted limits,
`{ ;i'sTn-:i·bal 'koz l
`thereby alte1ing quality.
`assignment problem
`[COMPUT SCI) A special case of the
`transportation problem in a linear program, in which the number
`of sources (assignees) equals the number of designations
`(assignments) and each supply and each demand equals I.
`{ a'sin·mant 'prab·l:im l
`assignment statement
`[ COMPUT SCI) A statement in a com(cid:173)
`puter program that assigns a value to a variable. { a'sin·mant
`,stat·m:int j
`assili cotton
`[TEXT) A long-staple Egyptian cotton charac(cid:173)
`terized by high tensile strength. { 'a·s:i·lc ,ktit·;m l
`assimilation
`[GEOL]
`Incorporation of solid or fluid material
`that was originally in the rock wall into a magma.
`[PHYSIO)
`The conversion of nutritive materials
`into protoplasm.
`{ a,sim·a'la·sh;in l
`assimilative nitrate reduction
`[MICROBIO) The reduction
`of nitrates by some aerobic bacteria for purposes of assimilation.
`{ a,sim·a'lad·iv 'nI,trat ri,dak·shan }
`assimilative sulfate reduction
`[MICROIJIO) The reduction
`of sulfates by certain obligate anaerobic bactetia for purposes
`of assimilation. { a,sim·a'lad·iv 'sal,fat ri,d;ik·shan )
`assisted panel
`[COMPUT scI]
`In an interactive system, a
`screen that explains a question the computer has asked, the
`available options, the expected format, and so forth.
`{ ;i'sis·
`tad 'pan·al }
`assisted takeoff
`[AERO ENG] A takeoff of an aircraft or a
`missile by using a supplementary source of power, usually
`{ a'sis·tad 'tak,of l
`rockets.
`assize
`[CIV ENG) 1. A cylinddcal block of stone forming
`one unit in a column. 2. A layer of stonework.
`{ a'sTz }
`Assmann psychrometer
`[ENG) A special form of the aspi(cid:173)
`ration psychrometer in which the the1momettic elements are
`l 'iis,miin ,si'kram·ad·;ir l
`well shielded from radiation.
`associate
`[PSYCH] An item or event that is linked to another
`in the mind of an individual. { a'so·sc,at }
`associate curve See Bertrand curve.
`{ ;i'so·se•gt ,k;irv }
`l ;i'so·
`associated automatic movement See synk:inesia.
`se,ad·::id :od·;i'mad·ik 'milv·m~,nt }
`associated corpuscular,< emission
`[GEOPHYs] The full
`complement of secondary charged pruticles associated with the
`passage of an x-ray or gamma-ray beam through air. { ;:,'so·
`se,ad•;:id ,kor'p;is·ky;:,•lar'fmish•gn l
`associated document
`[COMPUT sci] A file that is linked
`Lo Lhe application program in which it was created, so that the
`application can be started by choosing such a file.
`{ g 1so·
`se,ad•;id 'dlik·y"-m"nt }
`associated gas
`hydrocmbons
`[PETRO ENG) G~eous
`occurring as a free-gas phase under original oil-reservoir condi(cid:173)
`tions of temperature and pressure. Also known as gas-cap
`gas. { a'sO·se,ad·gd 1gas }
`
`associated prime ideal
`[MATH) A prime ideal l in a com(cid:173)
`mutative ring R is said to be associated with a module Mover
`R if there exists an element x in M such that l is the annihilator
`l ;i'so·se,ad·ad 'prim ,I·del }
`of x.
`associated production
`[PARTIC PHYS] Production of
`strange particles invariably in twos, never one particle alone.
`{ :i'so·se,ad•;,id pr::i'dak·shan }
`associated radii of convergence
`[MATH) For a power
`series in II vmiables, Zi, .. , z111 any set of numbers, r 1, •• , rm
`such that the series converges when Id < r,, i = I, .. , n, and
`diverges when Id > r;, i = l, .. ,,,.
`{ a:so·se,ad·ad :racl-tle,l
`gv kan'var·jans }
`associated tensor
`[MATH) A tensor obtained by taking the
`inner product of a given tensor with the metric tensor, or by
`pe1forming a series of such operations. { ;i'so·sc,ad·;id
`'ten·s:ir l
`associate matrix See 1-Iennitian conjugate. { ::i'so·se•gt
`'ma·triks}
`associate operator See adjoint operator. { ;i'so·se•;,it 'iip·
`a,rad·:ir }
`[MATH) Two elements x and yin a commutative
`associates
`ring with identity such that x = ay, where a is a unil. Also
`l ;i'so·se·atz l
`known as equivalent elements.
`association
`[ASTRON) A sparsely populated grouping of
`very young stars that appear to have had a common origin and
`have not yet had time to disperse.
`[Cl·IEM) Combination or
`correlation of substances or functions.
`[ECOL] Major seg(cid:173)
`ment of a biome fanned by a climax community, such as an
`[PSYCH]
`oak-hickory forest of the deciduous forest biome.
`A connection fanned through learning. { ;,i,so·se'a·sh;,in }
`association area
`[PHYS!O) An area of the cerebral cortex
`that is thought to link and coordinate activities of the projection
`{ :J 1s6•se 1a·shan 1er·e-~}
`areas.
`association center
`In invertebrates, a nervous
`[INV zoo]
`center coordinating and distributing stimuli from sensory recep(cid:173)
`l a,so·se'a·sh;in ,sen·tar }
`tors.
`association constant
`[mocHEM) A quantitative desc1ip(cid:173)
`tion of the affinity of a ligand for a protein that binds to it.
`{ a,so·se'a·sh;in :kan·stant}
`association fiber
`[NEURO] One of the white nerve fibers
`situated just beneath the cortical substance and connecting the
`adjacent cerebral gyri. { '1,so·se'a·shan ,fi-b;ir l
`association neuron
`[NEURO) A neuron, usually within the
`central nervous system, between sensory and motor neurons.
`{ ::i,so·se'a·sh;in 'mi,ran l
`association test
`[PSYCH) Any test designed to detennine
`the nature of the mental or emotional link between a stimulus
`{ :i,so·se'ii·sh;,in ,test)
`and a response.
`association trail
`[COMPUT sci] A linkage between two or
`more documents or items of information, discerned <luting the
`process of their examination and recorded with the aid of an
`information retrieval system.
`{ ::i,so·se'a·sh:in ,trfil }
`associative algebra
`[MATH) An algebra in which the vector
`multiplication obeys the associative law.
`{ :i'so·se,ad·iv 'al·
`j::i·bra l
`associative dimensioning system
`[COMPUT SCI] A system
`for making automatic changes in the dimensions of workpieces
`l a'so·se,ad·iv di'men-shan·
`manufactured by machine tools.
`il] 'sis·t;im J
`associative facilitation
`[PSYCH) Ease in establishing a new
`association because of previous associations. { g'so·se,ad·iv
`fo,sil·a'ta·shan l
`associative inhibition
`[PSYCH) Difficulty in establishing a
`new association because of previous associations.
`{ g'so·
`se,ad·iv ,in•g'bish·an }
`associative key
`In a computer system with
`[COMPUT SCI)
`an associative memory, a field used to reference items through
`comparing the value of the field with corresponding fields in
`each memory cell and retrieving the contents of matching cells.
`{ :i'sii·se,ad·iv 'kc }
`associative law
`[MATH) For a bina1y operation that is desig(cid:173)
`nated 0 , the relationship expressed by a O (I, 0 c) = (a O /,) 0 c.
`l a'so·se,ad·iv 'lo }
`associative learning
`items
`that
`[PSYCH) The principle
`experienced together are mentally linked so that they Lend to
`reinforce one another. { ;,i'so·se,iid·iv 'l::,rn•iIJ }
`associative memory
`[COMPUT SCI] A data-storage device
`in which a location is identified by its informational content
`rather than by names, addresses, or relative positions, and from
`
`4
`
`

`

`driving signal
`
`653
`
`DRIVEN CAISSON
`
`0
`
`cylindrical
`steel casing ----(cid:173)
`""'
`
`soil
`
`Driven caisson, top view and cross(cid:173)
`section from the side.
`
`4
`
`drill weave
`
`detail; for example, viewing total sales as opposed to individual
`sales.
`{ :dril ';ip }
`drill weave
`[TEXT) Special fabric sometimes used in filtra(cid:173)
`tion; a three-harness, warp-face twill weave, having the two(cid:173)
`up and one-down twill effect. { 'dril , wev }
`[INV zoo] A superfamily of parasitic
`Drilonernatoidea
`nematodes in the subclass Spiruria.
`( ,drI·lo,ncm·a't6id·e·;i}
`drip
`[ARCH)
`See hoodmold.
`[HYD) Condensed or other(cid:173)
`wise collected moisture falling from leaves, twigs, and so forth.
`[MATER) 1. Oil which comes through the cloth of a paraffin
`wax press. 2. Filter drainings too dark to be included in filter
`[PETil.O ENG) A discharge mechanism installed at a
`stock.
`low point in a gas transmission line to collect and remove
`( drip }
`liquid accumulations. Also known as blowcase.
`drip cap
`[BUILD) A horizontal molding installed over the
`frame for a door or window to direct water away from the
`frame.
`{ 'drip ,kap }
`drip-dry
`[TEXT) Of a fabric, shedding water or moisture rap(cid:173)
`idly without squeezing, spinning, or wringing.
`( 'drip ,drI ]
`drip edge
`[BUILD) A metal strip that extends beyond the
`other parts of the roof and is used to direct rainwater off.
`( 'drip ,ej }
`drip irrigation
`[AGR) A method of providing water to plants,
`almost continuously, through small-diameter tubes and emitters.
`{ 'drip ,ir·i,ga·sh~m }
`[Nuc PHYS) The boundary, on a chart of the
`drip line
`nuclides, beyond which a nucleon (proton or neutron) is no
`longer bound to the nucleus. { 'drip ,!In ]
`dripping drop atomization
`[HYO] A type of natural gravita(cid:173)
`tional atomization process in which there is periodic emission
`of drops from the bottom side of a surface to which a liquid
`is fed continuously, as in dripping of water from leaves.
`{ :drip·iIJ :drtip ,ad·;i·m;i'za·sh;in}
`dripstone
`[GE0L) A cave feature, such as a stalagmite,
`which is formed by precipitation of calcium carbonate or
`another mineral from dripping water.
`( 'drip,ston }
`drive
`[ELECTR)
`See excitation.
`[MECH ENG] The means
`by which a machine is given motion or power (as in steam
`drive, diesel-electric drive), or by which power is transferred
`from one part of a machine to another (as in gear drive, belt
`[MIN ENG) 1. To excavate in a horizontal or inclined
`drive).
`plane. 2. A horizontal underground tunnel along or parallel
`to a lode, vein, or ore body.
`[PSYCH) A strong impetus to
`behavior or active striving.
`{ d1iv )
`drive array
`[C0MPUT SCI) A collection of hard disks orga(cid:173)
`nized to increase speed and improve reliability, often with the
`help of data stripping.
`( 'driv a,ra }
`drive bay
`[COMPUT SCI] A space in the cabinet of a personal
`computer where disk drives, tape drives, and CD-ROM drives
`can be installed. Also known as bay.
`{ 'diiv ,ba }
`drive-by-wire
`[MECH ENG] Electronic throttle control in
`automobiles.
`{ :driv bI 'wir )
`drive chucl<
`[MECH ENG] A mechanism at the lower end of
`a diamond-drill drive rod on the swivel head by means of which
`the motion of the drive rod can be transmitted to the drill string.
`{ driv ,ch;ik )
`drive control See horizontal drive control.
`( 'dr'lv bn,trol )
`drive fit
`[DES ENG) A fit in which the larger (male) part is
`pressed into a smaller (female) part; the assembly must be
`effected
`through
`the application of an external
`force.
`( ,driv ,fit}
`drivehead
`[ENG) A cap fitted over the end of a mechanical
`part to protect it while it is being driven.
`( 'driv,hed }
`driveless work station
`[cOMPUT sci] A computer or termi-
`nal in a local area network that clqes not have its own disk
`drives and relies on a central mass storage facility for infom1a(cid:173)
`( 'driv•l;is 'wark,slil·sh~ }
`tion storage.
`drive light
`[COMPUT SCI) A lam'(:> on the front of a disk drive
`that lights to indicate when the unit is reading or writing data.
`( 'driv ,In }
`\.
`driveline
`[MEC!i, ENG]
`In an automotive vehicle, the group
`of parts, including the universal joint and the drive shaft, that
`connect the transmission with the driving wheels.
`( 'driv,!In }
`driven array
`[ELECTR0MAG] An antenna an-ay consisting of
`a number of driven elements, usually half-wave dipoles, fed
`{ :driv·
`in phase or out of phase from a common smlrce.
`;in ;i'rH )
`driven blocking oscillator See monostable blocking oscillator.
`[ :driv·;in :bHik·iIJ 'as·a,lad·ar }
`
`driven caisson
`fc1v ENG] A caisson formed by driving a
`cylindrical steel shell into the ground with a pile-driving ham(cid:173)
`mer and then placing concrete inside; the shell may be removed
`when concrete sets.
`{ :driv•;in 'ka,san )
`driven element
`[ELECTROMAG) An antenna element that is
`( :c1riv•;in 'el•;i•
`directly connected to the transmission line.
`mant}
`driven gear
`[MECH ENG) The member of a pair of gears to
`{ :c1riv·
`which motion and power are transmitted by the other.
`gn 1gir}
`driven snow
`[METEOROL] Snow which has been moved by
`wind and collected into snowdrifts.
`( :c1riv·;in 'sno )
`drive pattern
`[COMMUN)
`In a facsimile system, undesired
`pattern of density variations caused by periodic e1rnrs in the
`position of the recording spot.
`( 'driv ,pad·;irn }
`drivepipe
`[ENG) A thick-walled casing pipe that is driven
`through overburden or into a deep drill hole to prevent cav(cid:173)
`ing.
`( 'driv,pip }
`[MECH ENG) The pulley that drives a conveyor
`drive pulley
`belt.
`( 'driv ,pi1l·e }
`drive pulse
`[ELECTR] An electrical pulse which induces a
`magnetizing force in an element of a 111agnetic core storage,
`reversing the polarity of the core.
`( 'driv ,p;,ls }
`driver
`[COMPUTSCI) A sequence of program instructions that
`controls an input/output device such as a tape drive or disk
`drive.
`[ELECTR) The amplifier stage preceding the output
`stage in a receiver or transmitter.
`[ENG ACOUS] The portion
`of a horn loudspeaker that converts electrical energy into acous(cid:173)
`tical energy and feeds the acoustical energy to the small end
`of the horn.
`{ 'drI·v;ir }
`driver element
`[ELECTROMAG] Antenna array element that
`{ 'drf• v;:,r ,el·
`receives power directly from the transmitter.
`:i·m::mt}
`drive rod
`[ENG) Hollow shaft in the swivel head of a dia(cid:173)
`mond-drill machine through which energy is transmitted from
`the drill molar to the drill string. Also known as drive spindle.
`( 'driv ,rad }
`driver sweep
`[ELECTR) Sweep triggered only by an incom(cid:173)
`( 'drI·v;,r ,swep }
`ing signal or trigger.
`driver transformer
`[ELEC11t) A transformer in the input cir(cid:173)
`cuit of an amplifier, especially in the transmitter.
`( 'drI•v;:,r
`tranz'for·mar ]
`drive sampling
`[ENG) The act or process of driving a tubular
`device into soft rock material for obtaining dry samples.
`( 'dr'lv ,sam ·pliIJ }
`drivescrew
`[DES ENG] A screw that is driven all the way in,
`or nearly all the way in, with a hammer.
`( 'driv,skrli }
`drive shaft
`[MECH ENG) A shaft which transmits power from
`a molar or engine to the rest of a machine.
`( 'driv ,shaft }
`drive shoe
`[DES ENG) A sharp-edged steel sleeve attached
`to the bottom of a drivepipe or casing to act as a cutting edge
`and protector.
`( 'dr'lv ,shli }
`drive spindle See drive rod.
`( 'driv ,spin•d;il }
`drive train See power train.
`( 'driv ,tran }
`drive winding
`[ELECTR) A coil of wire that is inductively
`coupled to an element of a magnetic memmy. Also known
`as drive wire.
`( 'driv ,win·diIJ }
`drive wire See drive winding.
`( 'dr1v ,wir }
`driving clock
`[ENG) A mechanism for driving an instrument
`at a required rate.
`( 'driv·iIJ ,kltik }
`driving force
`[ CHEM)
`In a chemical reaction, the formation
`of products such as an insoluble compound, a gas, a none!ectro(cid:173)
`lyte, or a weak electrolyte that enable the reaction to go to
`completion as a metathesis.
`( 'clr'lv·il) ,fors }
`driving pinion
`[MECH ENG] The input gear in the differential
`of an automobile.
`( 'd1iV·i1J ,pin·y,:m )
`driving-point function
`[CONT SYS) A special type of trans(cid:173)
`fer function in which the input and output vmiables arc voltages
`or currents measured between the smne pair of terminals in an
`electrical network.
`{ 'driv·il) ,point, fol)k·shgn }
`driving-point impedance
`[ELECTR) The complex ratio of
`applied alternating voltage to the resulting alternating cun-ent
`in an electron tube, network, or other transducer.
`{ 'drfv•iIJ
`,point im'ped·ans )
`driving resistance
`[MECH] The force exerted by soil on a
`pile being driven into it.
`{ 'driv·iIJ ,i'zis·wns }
`driving signal
`[ELECTR] Television signal that times the
`scanning at the pickup point.
`( 'driv·il) ,sig•n;i! )
`
`5
`
`

`

`654
`
`driving wheel
`
`droppingmmercury electrode
`
`[VERT Zoo] The emus, a monospecific family
`birds
`in
`the order Casuariifonnes.
`{ ,dr5·
`
`driving wheel
`[MECH ENG] A wheel that supplies driving
`power.
`{ 'drTv•iJJ ,we! }
`drizzle
`[METEOROL] Very small, numerous, anci uniformly
`dispersed water drops that may appear lO float while following
`air currents; unlike fog droplets, drizzle falls to the ground; it
`usually falls from low stratus clouds and is frequently accompa(cid:173)
`[ 'driz·:.il J
`nied by low visibility anci fog.
`drizzle drop
`[METEOROL] A drop of water of diameter 0.2
`to 0.5 millimeter falling through the atmosphere; however, all
`water cirops of diameter greater than 0.2 millimeter are fre(cid:173)
`quently termed raindrops, as opposed to cloud drops.
`{ 'driz·
`al ,driip}
`DRM See detrilal remanent magnetization.
`drogue
`[AERO ENG] 1. A small parachute attached to a bociy
`for stabilization and deceleration. Also known as deceleration
`parachute. 2. A funnel-shaped device at the end of the hose
`of a tanker aircraft in flight, to receive the probe of another
`1. A device, such as a
`aircraft that will take on fuel.
`[ENG]
`sea anchor, usually shaped like a funnel or cone and ciraggcd
`or towed behind a boat or seaplane for deceleration, stabiliza(cid:173)
`tion, or speed control. 2. A current-measuring assembly con(cid:173)
`sisting of a weighted current cross, sail, or parachute and an
`attached surface buoy. Also known as drag anchor; sea
`anchor.
`{ drog }
`[VERT zoo] A family of the avian order Chara(cid:173)
`Dromadidae
`driiformes containing a single species, the crab plover (Dramas
`ardeola). { dro'mad•g,dc J
`dromedary
`[VERT ZOO] Came/us dromedarius The Arabian
`camel, distinguished by a single hump.
`[ 'dram·a,der·e }
`[!NV zoo l The dromiid crabs, a subsection of
`Dromiacea
`the Brachyura in the crustacean order Dccapoda.
`{ ,dro·me'a·
`she·a }
`Dromiceidae
`of flightless
`ma'se·::>,de }
`dromophobia
`[PSYCH] An abnormal fear of walking about.
`[ ,dro•mg'fo·be·;i }
`drone
`[AERO ENG] A pilotlcss aircraft usually subordinated
`to the controlling influences of a remotely located command
`[lNV zoo] A hap(cid:173)
`station, bul occasionally preprogrammed.
`loid male bee or ant; one of the three castes in a colony.
`{ dron }
`drooped ailerons
`[AERO ENG] Ailerons that are of the
`hinged trailing-edge type and are so arrangeci that both the
`right and left one have a IO to 15° positive downward deflection
`{ :drllpt 'a·
`with the control column in a neutral position.
`l:i,riins }
`droop governor
`[MECH ENG] A governor whose equilib(cid:173)
`rium speed decreases as the load on the machinery controllcci
`{ 1drUp 1gcl·v~r•ngr }
`by the governor increases.
`drop
`[f'L MECH] The quantity of liquid that coalesces into a
`single globule; sizes vary according to physical conditions and
`[HYD] The difference in
`the properties of the fluid itself.
`waler-surface elevations that is measured up-and downstream
`from a narrowing in the stream.
`[MET] A casting defect due
`to the falling of a portion of sand from an overhanging section
`of the mold.
`[MINERAL] A funnel-shaped downward intru(cid:173)
`sion of sedimentary rock into the roof of a coal scam.
`[PL
`Pi\TII] A fungus disease or various vegetables caused by Sc/e(cid:173)
`rotinia sclemtiorum and characterized by wilt and stem rot.
`{ driip}
`drop ball
`[ENG] A ball, weighing 3000-4000 pouncis
`( 1400-1800 kilograms), dropped from a crane through about
`20-33 feet (6-10 meters) onto oversize quarry stones left after
`blasting; Ihis method is used to avoid secondary blasting.
`{ 'drap ,bol l
`drop bar
`[ELECJ Protective device used to grounci a high(cid:173)
`[MECII ENG] A bar
`voltage capacitor when opening a door.
`thal guides sheets of pape