unilateral contract

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun law An agreement in which an offeror's offer can be accepted only by the performance of an act by the offeree; a "promise for a performance".

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a one-sided agreement whereby you promise to do (or refrain from doing) something in return for a performance (not a promise)