1. (v. i.) To act upon each other; as, two chemicals interact\.

2. (n.) A short act or piece between others, as in a play; an interlude; hence, intermediate employment or time.

accord act in concert act together affiliate agree ally amalgamate associate band band together be in cahoots be in league club together coadunate coalesce coincide collaborate collude combine concert concord concur confederate conjoin connive consolidate conspire cooperate correspond do business with dovetail engage federate fuse get heads together get together go partners hang together happen together harmonize hold together hook up interact interchange interlace intermesh interplay intertwine interweave interwork join join in join together keep together league league together make common cause merge mesh mortise partner play ball pull together put heads together reciprocate stand together synchronize synergize team up throw in together tie in tie up unite unite efforts work together