(of an expression or statement) performing an act by the very fact of being uttered, as with the expression “I promise,” that performs the act of promising.
per·for·ma·tive (pər-fôr'mə-tĭv) adj. Relating to or being an utterance that peforms an act or creates a state of affairs by the fact of its being uttered under appropriate or conventional circumstances, as a justice of the peace uttering I now pronounce you husband and wife at a wedding ceremony, thus creating a legal union, or as one uttering I promise, thus performing the act of promising. n. A performative utterance.