Source : Webster's Revised Unabridged Dictionary (1913)

Cenogamy \Ce*nog"a*my\ (s[-e]*n[o^]g"[.a]*m[y^]), n. [Gr.
   koino`s common + ga`mos marriage.]
   The state of a community which permits promiscuous sexual
   intercourse among its members, as in certain societies
   practicing communism.