parallel

UK: /ˈpærəlɛl/ US: /ˈpærəˌlɛl, -ləl/ ,(par′ə lel′, -ləl)

Inflections of 'parallel' (v): (⇒ conjugate)

When both "l" and "ll" forms exist, spellings with a double "l" are correct, but rare, in US English, while those with a single "l" are not correct in UK English.

parallels

v 3rd person singular

parallelling

v pres p (Mainly UK)

paralleling

v pres p (US)

parallelled

v past (Mainly UK)

paralleled

v past (US)

parallelled

v past p (Mainly UK)

paralleled

v past p (US)

WordReference Random House Learner's Dictionary of American English © 2025

par•al•lel /ˈpærəˌlɛl, -ləl/   adj., n., v., -leled, -lel•ing or (esp. Brit.) -lelled, -lel•ling, adv. 
adj. 

1. (of two or more items) lined up in the same direction, never meeting or spreading apart:
   parallel rows of chairs.
   [be + ~ + to]
   The highway was parallel to the old country road for a few miles.
2. having the same direction, tendency, or course:
   parallel interests.
3. Computing
   • Computing of or relating to operations within a computer performed at the same time:
     parallel processing.
   • Computing relating to or supporting the transfer of electronic data by several bits at a time:
     a parallel printer.

n. 

4. Mathematics [countable] a parallel line or plane.
5. anything parallel or comparable in direction, course, nature, or tendency to something else:
   [countable] parallels between human sacrifice and the Christian rite of Holy Communion.
   [uncountable] a case that has no parallel.
6. Place Names [countable] any of the imaginary lines on the earth's surface, parallel to the equator, that mark latitude.
7. Electricity an arrangement of an electrical circuit in which all positive terminals are connected to one point and all negative ones to another:
   [uncountable] batteries arranged in parallel.

v. [~ + object]

8. to provide a parallel for;
   match;
   equal:
   The rate of inflation paralleled the price of oil.
9. to be in a parallel course to:
   The road parallels the river.

adv. 

10. in a parallel course or manner:
    The river runs parallel to the main street.

par•al•lel•ism, n. [uncountable]

WordReference Random House Unabridged Dictionary of American English © 2025

par•al•lel  (par′ə lel′, -ləl), adj., n., v., -leled, -lel•ing or (esp. Brit.) -lelled, -lel•ling. 
adj. 

1. extending in the same direction, equidistant at all points, and never converging or diverging:
   parallel rows of trees.
2. having the same direction, course, nature, or tendency;
   corresponding;
   similar;
   analogous:
   Canada and the U.S. have many parallel economic interests.
3. Mathematics [Geom.]
   • (of straight lines) lying in the same plane but never meeting no matter how far extended.
   • (of planes) having common perpendiculars.
   • (of a single line, plane, etc.) equidistant from another or others (usually fol. by to or with).
4. Electricity consisting of or having component parts connected in parallel:
   a parallel circuit.
5. Music and Dance
   • (of two voice parts) progressing so that the interval between them remains the same.
   • (of a tonality or key) having the same tonic but differing in mode.
6. Computing
   • of or pertaining 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.
   • of or pertaining 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).

n. 

7. Mathematics a parallel line or plane.
8. anything parallel or comparable in direction, course, nature, or tendency to something else.
9. Geography, Place Names Also called parallel of latitude. 
   • Place Names 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.
   • Place Names the line representing this circle on a chart or map.
10. something identical or similar in essential respects;
    match;
    counterpart:
    a case history without a known parallel.
11. correspondence or analogy:
    These two cases have some parallel with each other.
12. a comparison of things as if regarded side by side.
13. 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. Cf. series (def. 9).
14. [Fort.] a trench cut in the ground before a fortress, parallel to its defenses, for the purpose of covering a besieging force.
15. Printing a pair of vertical parallel lines (∥∥) used as a mark for reference.
16. Show Business [Theat.] a trestle for supporting a platform (parallel top.)

v.t. 

17. to provide or show a parallel for;
    match.
18. to go or be in a parallel course, direction, etc., to:
    The road parallels the river.
19. to form a parallel to;
    be equivalent to;
    equal.
20. to show the identity or similarity of;
    compare.
21. to make parallel.

• Greek parállēlos side by side, equivalent. to par- par- + állēlos one another; see allo-, else
• Latin parallēlus
• 1540–50

par′al•lel′a•ble, adj. 
par′al•lel′less, adj. 
par′al•lel′ly, adv. 
Synonyms

• 2. like, alike.
• 10. equivalent, equal, mate, duplicate, twin, double.

Antonyms

• 2. divergent; unlike; unique.
• 10. opposite.

Collins Concise English Dictionary © HarperCollins Publishers::

parallel / ˈpærəˌlɛl/ adjective
when postpositive, usually followed by to:

1. separated by an equal distance at every point; never touching or intersecting: parallel walls
2. corresponding; similar: parallel situations
3. Also: consecutive (of two or more parts or melodies) moving in similar motion but keeping the same interval apart throughout: parallel fifths
4. denoting successive chords in which the individual notes move in parallel motion
5. denoting syntactic constructions in which the constituents of one construction correspond to those of the other
6. operating on several items of information, instructions, etc, simultaneously
   Compare serial6

noun

1. one of a set of parallel lines, planes, etc
2. an exact likeness
3. a comparison
4. 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
5. (as modifier): a parallel circuit
   See series6

verb ( -lels, -leling, -leled)(transitive)

1. to make parallel
2. to supply a parallel to
3. to be a parallel to or correspond with: your experience parallels mine

Etymology: 16th Century: via French and Latin from Greek parallēlos alongside one another, from para-¹ + allēlos one another