Pronunciation: (bī-lat'ur-ul),[key] —adj. 1. pertaining to, involving, or affecting two or both sides, factions, parties, or the like: a bilateral agreement; bilateral sponsorship. 2. located on opposite sides of an axis; two-sided, esp. when of equal size, value, etc.
3. Biol.pertaining to the right and left sides of a structure, plane, etc.
4. Chiefly Law.(of a contract) binding the parties to reciprocal obligations.
5. through both parents equally: bilateral affiliation. Cf. unilateral (def. 7).
—n. Informal.a bilateral agreement, esp. regarding international trade.