A term derived from the work of the philosopher J. L. Austin (1911-60), and now used widely in linguistics, to refer to a theory which analyses the role of utterances in relation to the behaviour of speaker and hearer in interpersonal communication. It is not an ‘act of speech’, but a communicative activity, defined with reference to the intentions of speakers while speaking (the illocutionary force of their utterances) and the effects they achieve on listeners (the perlocutionary effect of their utterances). Several categories of speech act have been proposed, viz. directives, commissives, expressives, declarations and representatives. The verb which are used to indicate the speech act intended by the speaker are sometimes known as performative verbs. The criteria which have to be satisfied in order for a speech act to be successful are known as felicity conditions.