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.
Geometry.
a.
(of straight lines) lying in the same plane but never meeting no matter how far extended.
b.
(of planes) having common perpendiculars.
c.
(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.
a.
(of two voice parts) progressing so that the interval between them remains the same.
b.
(of a tonality or key) having the same tonic but differing in mode.
6.
Computers.
a.
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.
b.
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).
–noun
7.
a parallel line or plane.
8.
anything parallel or comparable in direction, course, nature, or tendency to something else.
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.
b.
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. Compare series(def. 9).
14.
Fortification. 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.
Theater. a trestle for supporting a platform (parallel top).
–verb (used with object)
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.
Origin: 1540–50; < L parallēlus < Gk parállēlos side by side, equiv. to par-par-+ állēlos one another; see allo-, else
parallel (pār'ə-lěl') Pronunciation Key
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.
[par-uh-lel, -luh
l] 
adjective, noun, verb, -leled, -lel⋅ing or (especially British