accompaniment, accordance, agreement, alliance, association, bipartisanship, cahoots, co-working, coaction, coadjuvancy, coadministration, coagency, cochairmanship, codirectorship, coincidence, collaborativeness, collectivism, collectivity, collusion, combination, combined effort, commensalism, common effort, common enterprise, communalism, communism, communitarianism, community, complicity, concert, concerted action, concomitance, concord, concordance, concourse, concurrence, confluence, conjunction, consilience, conspiracy, cooperation, cooperativeness, correspondence, duet, duumvirate, ecumenicalism, ecumenicism, ecumenism, esprit, esprit de corps, fellow feeling, fellowship, fifth-column activity, fraternization, harmony, high treason, joining of forces, joint effort, joint operation, junction, lese majesty, mass action, misprision of treason, morale, mutual assistance, mutualism, mutuality, octet, parasitism, petty treason, pooling, pooling of resources, pulling together, quartet, quintet, quislingism, reciprocity, saprophytism, sedition, septet, sextet, simultaneity, solidarity, symbiosis, synchronism, synergism, synergy, team spirit, teamwork, treason, trio, triumvirate, troika, union, united action