troika (n.)
- clover
- coaction
- collaboration
- collectivism
- collusion
- commensalism
- communalism
- communism
- community
- complicity
- concert
- concord
- concordance
- concurrence
- cooperation
- cooperativeness
- deuce-ace
- duet
- ecumenicalism
- ecumenicism
- ecumenism
- esprit
- fellowship
- harmony
- leash
- morale
- mutualism
- mutuality
- octet
- quartet
- quintet
- reciprocity
- septet
- sextet
- shamrock
- solidarity
- symbiosis
- synergism
- synergy
- teamwork
- tercet
- ternary
- ternion
- terzetto
- three
- threesome
- tierce
- trefoil
- trey
- triad
- triangle
- tricorn
- trident
- trilogy
- trimester
- trine
- trinity
- trio
- triple
- triplet
- tripod
- triptych
- trireme
- triskelion
- triumvirate
- trivet
