Source : Webster's Revised Unabridged Dictionary (1913)

Couplet \Coup"let\ (-l?t), n. [F. couplet, dim. of couple. See
   {Couple}, n. ]
   Two taken together; a pair or couple; especially two lines of
   verse that rhyme with each other.

         A sudden couplet rushes on your mind.    --Crabbe.

Source : WordNet®

couplet
     n 1: two items of the same kind [syn: {couple}, {pair}, {twosome},
           {twain}, {brace}, {span}, {yoke}, {distich}, {duo}, {duet},
           {dyad}, {duad}]
     2: a stanza consisting of two successive lines of verse;
        usually rhymed