The effect of an utterance
that it has as a by
-product of being uttered.
If I say "the inspectors will be here at noon" I might merely be passing on a fact, but this utterance could have various effects on you. It might frighten you, because they'll discover your embezzlement. Or it might spur you to neaten up your desk. Or it might remind you to get your blowdart refilled. These are all perlocutionary effects.
It is in contrast to illocutionary force. The term is due to J.L. Austin.