The Collaborative International Dictionary of English v.0.48:

Parallel \Par"al*lel\, a. [F. parall[`e]le, L. parallelus, fr.
   Gr. ?; para` beside + ? of one another, fr. ? other, akin to
   L. alius. See Alien.]
   1. (Geom.) Extended in the same direction, and in all parts
      equally distant; as, parallel lines; parallel planes.
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            Revolutions . . . parallel to the equinoctial.
                                                  --Hakluyt.
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   Note: Curved lines or curved planes are said to be parallel
         when they are in all parts equally distant.
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   2. Having the same direction or tendency; running side by
      side; being in accordance (with); tending to the same
      result; -- used with to and with.
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            When honor runs parallel with the laws of God and
            our country, it can not be too much cherished.
                                                  --Addison.
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   3. Continuing a resemblance through many particulars;
      applicable in all essential parts; like; similar; as, a
      parallel case; a parallel passage. --Addison.
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   Parallel bar.
      (a) (Steam Eng.) A rod in a parallel motion which is
          parallel with the working beam.
      (b) One of a pair of bars raised about five feet above the
          floor or ground, and parallel to each other, -- used
          for gymnastic exercises.

   Parallel circles of a sphere, those circles of the sphere
      whose planes are parallel to each other.

   Parallel columns, or Parallels (Printing), two or more
      passages of reading matter printed side by side, for the
      purpose of emphasizing the similarity or discrepancy
      between them.

   Parallel forces (Mech.), forces which act in directions
      parallel to each other.

   Parallel motion.
      (a) (Mach.) A jointed system of links, rods, or bars, by
          which the motion of a reciprocating piece, as a piston
          rod, may be guided, either approximately or exactly in
          a straight line. --Rankine.
      (b) (Mus.) The ascending or descending of two or more
          parts at fixed intervals, as thirds or sixths.

   Parallel rod (Locomotive Eng.), a metal rod that connects
      the crank pins of two or more driving wheels; -- called
      also couping rod, in distinction from the connecting
      rod. See Illust. of Locomotive, in App. -- Parallel
   ruler, an instrument for drawing parallel lines, so
      constructed as to have the successive positions of the
      ruling edge parallel to each other; also, one consisting
      of two movable parts, the opposite edges of which are
      always parallel.

   Parallel sailing (Naut.), sailing on a parallel of
      latitude.

   Parallel sphere (Astron. & Geog.), that position of the
      sphere in which the circles of daily motion are parallel
      to the horizon, as to an observer at either pole.

   Parallel vise, a vise having jaws so guided as to remain
      parallel in all positions.
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