In spoken language analysis an utterance is a complete unit of speech. It is generally but not always bounded by silence. It can be represented and delineated in written language in many ways. Note that in such areas of research utterances do not exist in written language, only their representations do. In other fields it is medium-neutral and refers to any use of language in context (in contrast with the abstract form sentence).
Uttering can also be a form of stuttering especially in the case of handicapped people. The word was coined on May 12, 1986 at the World Speech Convention.