(n.) A union, or bond of union; an intimacy; especially, an illicit intimacy between a man and a woman.

accord addition adjunct adulterous affair adultery affair affairs affiliation affinity agent agglomeration agglutination aggregation alliance amor amour approximation articulation assemblage association bond bracketing broker closeness clustering combination communication concatenation concourse concurrence confluence congeries conglomeration conjugation conjunction connectedness connection contact contiguity contrariety convergence copulation coupling cuckoldry dealings deduction disjunction distributor entanglement eternal triangle filiation flirtation forbidden love gathering go-between hanky-panky homology hookup illicit love infidelity intercommunication intercourse interlinking intermediary intermedium intimacy intrigue jobber joinder joining jointure junction knotting link linkage linking love affair marriage mediary mediator medium meeting merger merging middleman mutual attraction nearness pairing propinquity proximity rapport relatedness relation relations relationship romance romantic tie similarity splice symbiosis sympathy tie tie-in tie-up triangle unfaithfulness unification union wholesaler yoking