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[par-uh-lel, -luh l] /ˈpær əˌlɛl, -ləl/
extending in the same direction, equidistant at all points, and never converging or diverging:
parallel rows of trees.
having the same direction, course, nature, or tendency; corresponding; similar; analogous:
Canada and the U.S. have many parallel economic interests.
  1. (of straight lines) lying in the same plane but never meeting no matter how far extended.
  2. (of planes) having common perpendiculars.
  3. (of a single line, plane, etc.) equidistant from another or others (usually followed by to or with).
Electricity. consisting of or having component parts connected in parallel:
a parallel circuit.
  1. (of two voice parts) progressing so that the interval between them remains the same.
  2. (of a tonality or key) having the same tonic but differing in mode.
  1. of or relating to the apparent or actual performance of more than one operation at a time, by the same or different devices (distinguished from serial):
    Some computer systems join more than one CPU for parallel processing.
  2. of or relating to the simultaneous transmission or processing of all the parts of a whole, as all the bits of a byte or all the bytes of a computer word (distinguished from serial).
a parallel line or plane.
anything parallel or comparable in direction, course, nature, or tendency to something else.
Also called parallel of latitude. Geography.
  1. an imaginary circle on the earth's surface formed by the intersection of a plane parallel to the plane of the equator, bearing east and west and designated in degrees of latitude north or south of the equator along the arc of any meridian.
  2. the line representing this circle on a chart or map.
something identical or similar in essential respects; match; counterpart:
a case history without a known parallel.
correspondence or analogy:
These two cases have some parallel with each other.
a comparison of things as if regarded side by side.
Electricity. an arrangement of the components, as resistances, of a circuit in such a way that all positive terminals are connected to one point and all negative terminals are connected to a second point, the same voltage being applied to each component.
Compare series (def 9).
Fortification. a trench cut in the ground before a fortress, parallel to its defenses, for the purpose of covering a besieging force.
Printing. a pair of vertical parallel lines (‖) used as a mark for reference.
Theater. a trestle for supporting a platform (parallel top)
verb (used with object), paralleled, paralleling or (especially British) parallelled, parallelling.
to provide or show a parallel for; match.
to go or be in a parallel course, direction, etc., to:
The road parallels the river.
to form a parallel to; be equivalent to; equal.
to show the identity or similarity of; compare.
to make parallel.
Origin of parallel
1540-50; < Latin parallēlus < Greek parállēlos side by side, equivalent to par- par- + állēlos one another; see allo-, else
Related forms
parallelable, adjective
parallelless, adjective
parallelly, adverb
nonparallel, adjective, noun
subparallel, adjective
unparallel, adjective
2. like, alike. 10. equivalent, equal, mate, duplicate, twin, double.
2. divergent; unlike; unique. 10. opposite. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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British Dictionary definitions for parallel processing

parallel processing

the performance by a computer system of two or more simultaneous operations


adjective when postpositive, usually foll by to
separated by an equal distance at every point; never touching or intersecting: parallel walls
corresponding; similar: parallel situations
  1. Also consecutive. (of two or more parts or melodies) moving in similar motion but keeping the same interval apart throughout: parallel fifths
  2. denoting successive chords in which the individual notes move in parallel motion
(grammar) denoting syntactic constructions in which the constituents of one construction correspond to those of the other
(computing) operating on several items of information, instructions, etc, simultaneously Compare serial (sense 6)
(maths) one of a set of parallel lines, planes, etc
an exact likeness
a comparison
Also called parallel of latitude. any of the imaginary lines around the earth parallel to the equator, designated by degrees of latitude ranging from 0° at the equator to 90° at the poles
  1. a configuration of two or more electrical components connected between two points in a circuit so that the same voltage is applied to each (esp in the phrase in parallel)
  2. (as modifier): a parallel circuit See series (sense 6)
(printing) the character (∥) used as a reference mark
a trench or line lying in advance of and parallel to other defensive positions
verb (transitive) -lels, -leling, -leled
to make parallel
to supply a parallel to
to be a parallel to or correspond with: your experience parallels mine
Word Origin
C16: via French and Latin from Greek parallēlos alongside one another, from para-1 + allēlos one another
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for parallel processing



1540s, from Middle French parallèle (16c.) and directly from Latin parallelus, from Greek parallelos "parallel," from para allelois "beside one another," from para- "beside" (see para- (1)) + allelois "each other," from allos "other" (see alias). As a noun from 1550s. Parallel bars as gymnastics apparatus are recorded from 1868.


1590s, from parallel (n.).

Online Etymology Dictionary, © 2010 Douglas Harper
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parallel processing in Science
Adjective  Of or relating to lines or surfaces that are separated everywhere from each other by the same distance.

Noun  Any of the imaginary lines encircling the Earth's surface parallel to the plane of the equator, used to represent degrees of latitude. See illustration at longitude.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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parallel processing in Culture

parallel processing definition

The use of many different computer processors to work on different parts of a problem simultaneously. This is one way of increasing the speed at which computers can work, with each processor working on a part of a larger problem. (Compare serial processing.)

Note: The SETI project recently introduced a parallel processing system that allows individuals to use their personal computers to analyze data and assist in the search for extraterrestrial life.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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parallel processing in Technology
(Or "multiprocessing") The simultaneous use of more than one computer to solve a problem. There are many different kinds of parallel computer (or "parallel processor"). They are distinguished by the kind of interconnection between processors (known as "processing elements" or PEs) and between processors and memory. Flynn's taxonomy also classifies parallel (and serial) computers according to whether all processors execute the same instructions at the same time ("single instruction/multiple data" - SIMD) or each processor executes different instructions ("multiple instruction/multiple data" - MIMD).
The processors may either communicate in order to be able to cooperate in solving a problem or they may run completely independently, possibly under the control of another processor which distributes work to the others and collects results from them (a "processor farm"). The difficulty of cooperative problem solving is aptly demonstrated by the following dubious reasoning:
If it takes one man one minute to dig a post-hole then sixty men can dig it in one second.
Amdahl's Law states this more formally.
Processors communicate via some kind of network or bus or a combination of both. Memory may be either shared memory (all processors have equal access to all memory) or private (each processor has its own memory - "distributed memory") or a combination of both.
Many different software systems have been designed for programming parallel computers, both at the operating system and programming language level. These systems must provide mechanisms for partitioning the overall problem into separate tasks and allocating tasks to processors. Such mechanisms may provide either implicit parallelism - the system (the compiler or some other program) partitions the problem and allocates tasks to processors automatically or explicit parallelism where the programmer must annotate his program to show how it is to be partitioned. It is also usual to provide synchronisation primitives such as semaphores and monitors to allow processes to share resources without conflict.
Load balancing attempts to keep all processors busy by allocating new tasks, or by moving existing tasks between processors, according to some algorithm.
Communication between tasks may be either via shared memory or message passing. Either may be implemented in terms of the other and in fact, at the lowest level, shared memory uses message passing since the address and data signals which flow between processor and memory may be considered as messages.
The terms "parallel processing" and "multiprocessing" imply multiple processors working on one task whereas "concurrent processing" and "multitasking" imply a single processor sharing its time between several tasks.
See also cellular automaton,symmetric multi-processing.
Usenet newsgroup: news:comp.parallel.
Institutions (, research groups (
The Free On-line Dictionary of Computing, © Denis Howe 2010
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