(n.) Mutual action or influence; interaction; as, the interplay of affection.

ESP alternation answer battledore and shuttlecock coact coaction commerce communication communion commutation complementary distribution concurrence congress connection contact conversation converse cooperate cooperation correspondence counterchange cross fire dealing dealings dovetail engage engagement exchange give-and-take information interact interaction interchange intercommunication intercommunion intercourse interlace interlacing intermesh intermeshing intermutation intertwine intertwining interweave interweaving interwork interworking lex talionis linguistic intercourse measure for measure mesh meshing message mortise mutual admiration mutual support mutual transfer mutuality permutation quid pro quo reciprocality reciprocation reciprocity reply response retaliation seesaw social intercourse something for something speaking speech speech circuit speech situation talking telepathy tit for tat touch traffic transposal transposition truck two-way communication