bedfellow

from WordNet (r) 3.0 (2006)

bedfellow
    n 1: a temporary associate; "politics makes strange bedfellows"
    2: a person with whom you share a bed

from The Collaborative International Dictionary of English v.0.48

Bedfellow \Bed"fel`low\, n.
   One who lies with another in the same bed; a person who
   shares one's couch.
   [1913 Webster] Bedfere

from Moby Thesaurus II by Grady Ward, 1.0

56 Moby Thesaurus words for "bedfellow":
      ace, adjunct, ally, amigo, associate, bedmate, bosom buddy,
      brother, brother-in-arms, buddy, bunkie, bunkmate, butty, camarade,
      chamberfellow, chum, classmate, coadjutor, cohort, colleague,
      comate, companion, company, compatriot, compeer, comrade,
      confederate, confrere, consociate, consort, copartner, crony,
      fellow, fellow member, fellow student, girl friend, gossip, mate,
      messmate, old crony, pal, pard, pardner, partner, playfellow,
      playmate, roommate, schoolfellow, schoolmate, shipmate,
      side partner, sidekick, teammate, workfellow, yokefellow,
      yokemate