WordNet (r) 3.0 (2006):

troika
    n 1: a Russian carriage pulled by three horses abreast
    2: the cardinal number that is the sum of one and one and one
       [syn: three, 3, III, trio, threesome, tierce,
       leash, troika, triad, trine, trinity, ternary,
       ternion, triplet, tercet, terzetto, trey, deuce-
       ace]
    3: a modern Russian triumvirate

Moby Thesaurus II by Grady Ward, 1.0:

102 Moby Thesaurus words for "troika":
   bipartisanship, clover, coaction, coadjuvancy, coadministration,
   coagency, cochairmanship, codirectorship, collaboration,
   collaborativeness, collectivism, collusion, commensalism,
   common effort, common enterprise, communalism, communism,
   communitarianism, community, complicity, concert, concord,
   concordance, concurrence, cooperation, cooperativeness, deuce-ace,
   duet, duumvirate, ecumenicalism, ecumenicism, ecumenism, esprit,
   esprit de corps, fellow feeling, fellowship, harmony,
   joining of forces, joint effort, joint operation, leash,
   mass action, morale, mutual assistance, mutualism, mutuality,
   octet, pooling, pooling of resources, pulling together, quartet,
   quintet, reciprocity, septet, set of three, sextet, shamrock,
   solidarity, symbiosis, synergism, synergy, team spirit, teamwork,
   tercet, ternary, ternion, terzetto, three, threesome, tierce,
   trefoil, trey, triad, trialogue, triangle, tricorn, trident,
   triennium, trihedron, trilogy, trimester, trine, trinity,
   trinomial, trio, triphthong, triple, triple crown, triple threat,
   triplet, triplopy, tripod, triptych, trireme, triseme, triskelion,
   trisul, triumvirate, triune, triunity, trivet, united action