performative

per·for·ma·tive  (pr-fôrm-tv)

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. Also called speech act.