interjection

An interjection is a part of speech used to express a sudden emotion or reaction, such as surprise, joy, pain, or attention. It is typically syntactically independent of the surrounding sentence and does not form a grammatical clause. In many languages interjections function as exclamations or standalone utterances and are marked in writing by punctuation or by changes in intonation.

In speech, interjections convey the speaker's affective stance and can serve as discourse markers or vocatives when addressing someone. They are often lexically fixed (for example wow, alas, hey) but may also be onomatopoeic (buzz, clang) or generalized sounds (uh, erm). They may appear as isolated utterances or embedded with a comma or dash when integrated into a larger discourse.

Common English interjections include oh, ah, wow, alas, ouch, hey, yikes, uh, eh, hmm, and bravo. The function of an interjection is primarily to express emotion or to draw attention; it typically does not carry tense, aspect, number, or person features, and it rarely participates in the syntactic structure of the sentence.

Across languages, interjections are highly variable in form and may be borrowed or created to suit phonological systems. Some analyses treat interjections as a distinct class within grammar or as pragmatic particles that convey attitude rather than content. Etymology often traces to sound imitation, exclamations, or responses to social interaction.