Pronunciation: (yOO"nu-lat'ur-ul),[key] —adj. 1. relating to, occurring on, or involving one side only: unilateral development; a unilateral approach. 2. undertaken or done by or on behalf of one side, party, or faction only; not mutual: a unilateral decision; unilateral disarmament. 3. having only one side or surface; without a reverse side or inside, as a Möbius strip.
4. Law. a. pertaining to a contract that can be formed only when the party to whom an offer is made renders the performance for which the offeror bargains.
b. pertaining to a contract in which obligation rests on only one party, as a binding promise to make a gift.
5. Bot.having all the parts disposed on one side of an axis, as an inflorescence.
6. through forebears of one sex only, as through either the mother's or father's line. Cf. bilateral (def. 5).
7. Phonet.(of an l-sound) characterized by passage of air on only one side of the tongue.