The Collaborative International Dictionary of English v.0.48:

Couple \Cou"ple\ (k[u^]p"'l), n. [F. couple, fr. L. copula a
   bond, band; co- + apere, aptum, to join. See Art, a., and
   cf. Copula.]
   1. That which joins or links two things together; a bond or
      tie; a coupler. [Obs.]
      [1913 Webster]

            It is in some sort with friends as it is with dogs
            in couples; they should be of the same size and
            humor.                                --L'Estrange.
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            I'll go in couples with her.          --Shak.
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   2. Two of the same kind connected or considered together; a
      pair; a brace. "A couple of shepherds." --Sir P. Sidney.
      "A couple of drops" --Addison. "A couple of miles."
      --Dickens. "A couple of weeks." --Carlyle.
      [1913 Webster]

            Adding one to one we have the complex idea of a
            couple.                               --Locke.
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            [Ziba] met him with a couple of asses saddled. --2
                                                  Sam. xvi. 1.
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   3. A male and female associated together; esp., a man and
      woman who are married or betrothed.
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            Such were our couple, man and wife.   --Lloyd.
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            Fair couple linked in happy, nuptial league.
                                                  --Milton.
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   4. (Arch.) See Couple-close.
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   5. (Elec.) One of the pairs of plates of two metals which
      compose a voltaic battery; -- called a voltaic couple or
      galvanic couple.
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   6. (Mech.) Two rotations, movements, etc., which are equal in
      amount but opposite in direction, and acting along
      parallel lines or around parallel axes.
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   Note: The effect of a couple of forces is to produce a
         rotation. A couple of rotations is equivalent to a
         motion of translation.
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The Collaborative International Dictionary of English v.0.48:

Couple \Cou"ple\, v. t. [imp. & p. p. Coupled (k[u^]p"'ld); p.
   pr. & vb. n. Coupling (k[u^]p"l[i^]ng).] [F. coupler, fr.
   L. copulare. See Couple, n., and cf. Copulate, Cobble,
   v.]
   [1913 Webster]
   1. To link or tie, as one thing to another; to connect or
      fasten together; to join.
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            Huntsman, I charge thee, tender well my hounds, . .
            .
            And couple Clowder with the deep-mouthed brach.
                                                  --Shak.
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   2. To join in wedlock; to marry. [Colloq.]
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            A parson who couples all our beggars. --Swift.
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The Collaborative International Dictionary of English v.0.48:

Couple \Cou"ple\, v. i.
   To come together as male and female; to copulate. [Obs.]
   --Milton. Bacon.
   [1913 Webster]

WordNet (r) 3.0 (2006):

couple
    n 1: a pair who associate with one another; "the engaged
         couple"; "an inseparable twosome" [syn: couple,
         twosome, duo, duet]
    2: a pair of people who live together; "a married couple from
       Chicago" [syn: couple, mates, match]
    3: a small indefinite number; "he's coming for a couple of days"
    4: two items of the same kind [syn: couple, pair, twosome,
       twain, brace, span, yoke, couplet, distich,
       duo, duet, dyad, duad]
    5: (physics) something joined by two equal and opposite forces
       that act along parallel lines
    v 1: bring two objects, ideas, or people together; "This fact is
         coupled to the other one"; "Matchmaker, can you match my
         daughter with a nice young man?"; "The student was paired
         with a partner for collaboration on the project" [syn:
         match, mate, couple, pair, twin]
    2: link together; "can we couple these proposals?" [syn:
       couple, couple on, couple up] [ant: decouple,
       uncouple]
    3: form a pair or pairs; "The two old friends paired off" [syn:
       pair, pair off, partner off, couple]
    4: engage in sexual intercourse; "Birds mate in the Spring"
       [syn: copulate, mate, pair, couple]

Moby Thesaurus II by Grady Ward, 1.0:

207 Moby Thesaurus words for "couple":
   a few, accouple, accumulate, affiliate, agglutinate, ally, amass,
   apply, arrange a match, articulate, assemble, associate, ball,
   band, band together, be in cahoots, be intimate, be made one,
   be spliced, become one, bind, bond, both, brace, bracket, bridge,
   bridge over, bunch, bunch up, cabal, cement, cement a union,
   centralize, chain, clap together, clot, club, club together,
   cluster, coalesce, cohabit, collect, combine, come together,
   commit adultery, comprise, concatenate, confederate, conglobulate,
   congregate, conjoin, conjugate, connect, consociate, conspire,
   contract matrimony, converge, copulate, correlate, couple up,
   couplet, cover, crowd, date, diddle, distich, double harness,
   double-harness, double-team, doublet, draw a parallel, duad, duet,
   duo, dyad, embrace, encompass, equate, espouse, federalize,
   federate, flock together, flow together, forgather, fornicate,
   frig, fuse, gang, gang around, gang up, gather, gather around,
   get hitched, give away, glue, go in partners, go in partnership,
   group, harness, have sex, have sexual relations, herd together,
   hitch, hive, hook up, hook up with, horde, huddle, identify,
   include, intermarry, interrelate, interwed, join, join forces,
   join fortunes with, join together, join up with, join with, knot,
   lay, lay together, league, lie with, link, look-alikes,
   lump together, make a match, make it with, make love, make one,
   make out, marry, marshal, mass, match, matching pair, mate, mates,
   meet, merge, mill, miscegenate, mobilize, mount, muster, nuptial,
   one or two, organize, pair, pair off, parallel, parallelize,
   partner, piece together, put together, rally, rally around, relate,
   relativize, remarry, rendezvous, rewed, roll into one, screw,
   seethe, serve, service, set, set of two, several, sleep with,
   solder, span, splice, stand together, stand up with,
   stick together, stream, surge, swarm, take in, take to wife, tape,
   team, team up, team up with, team with, the two, throng,
   throw in with, tie, tie in with, tie up with, twain, twins, two,
   twosome, unify, unionize, unite, unite in marriage, unite with,
   wed, weld, wive, yoke