The Bedford Glossary of Critical and Literary Terms - Ross Murfin 2018
Illocutionary act: A speech act involving a locution, or utterance, that performs a particular function. Introducing the term in How to Do Things with Words (1962), British “ordinary-language” philosopher John L. Austin characterized it as the “performance of an act in saying something as opposed to performance of an act of saying something.” Thus, an illocutionary act may assert something, or it may order, promise, question, threaten, and so forth.
EXAMPLE: The locution “I’ll take the children with me” has multiple illocutionary possibilities. It could be a simple assertion of truth, a promise, or even a threat.