WordNet (r) 3.0 (2006):

pair off
    v 1: form a pair or pairs; "The two old friends paired off"
         [syn: pair, pair off, partner off, couple]

Moby Thesaurus II by Grady Ward, 1.0:

74 Moby Thesaurus words for "pair off":
   affiliate, ally, associate, average, average out, avoid extremes,
   band together, be in cahoots, be made one, be spliced, become one,
   bracket, bunch, bunch up, cabal, cement a union, centralize, club,
   club together, come together, confederate, conjugate, consociate,
   conspire, contract matrimony, couple, couple up, double-harness,
   double-team, espouse, federalize, federate, gang, gang up,
   get hitched, go in partners, go in partnership, hook up with,
   intermarry, interwed, join forces, join fortunes with,
   join together, join up with, join with, league, marry, match, mate,
   miscegenate, organize, pair, partner, remarry, rewed, span,
   split the difference, stand together, stand up with,
   strike a balance, take the average, take to wife, team, team up,
   team up with, team with, throw in with, tie in with, tie up with,
   unionize, unite with, wed, wive, yoke