A declaration assuring that one will or will not do something; a vow. Something promised. Indication of something favorable to come; expectation: a promise of spring in the air. Indication of future excellence or success: a player of great promise. To commit oneself by a promise to do or give; pledge: left but promised to return. To afford a basis for expecting: thunderclouds that promise rain. To make a declaration assuring that something will or will not be done. To afford a basis for expectation: an enterprise that promises well.