interjectio

Interjectio, or interjection, is a linguistic term for a word or particle used to express emotion, attitude, or spontaneous reaction, often standing outside the syntactic structure of a sentence. In traditional grammar it is treated as a distinct part of speech.

Etymology and concept: The word derives from Latin interiectio, meaning “a throw between,” reflecting the idea of inserting an utterance into discourse. Interjections are typically not inflected and do not govern or take complements; they function as standalone vocalizations or discourse tokens.

Usage and features: Interjections convey affect such as surprise, pain, greeting, agreement, hesitation, or attention. They are often more about tone and affect than about propositional content. In writing, they may be punctuated with exclamation points or set off by parentheses or dashes, and they usually stand apart from the surrounding sentence grammar. Phonologically, they are frequently distinctive and may be onomatopoeic or mimetic.

Cross-linguistic variation: Almost all languages have interjections, though the forms and functions vary. English examples include oh, wow, ouch, hmm, and hey. Other languages offer specialized exclamations for pain, gratitude, or surprise, as well as greetings or attention-getters such as Spanish ¡ay! or Japanese ah, ee, or un. Some interjections are fixed expressions; others are phonetic approximations of sounds.

Classification and function: Interjections are sometimes grouped by semantic function (emotional expression, response, attention-getting) or by pragmatic role (stance markers, discourse signals). Some grammars treat interjections as a separate category; others categorize them as a broad, invariable set of exclamations or pragmatic particles.

See also: Exclamation, discourse marker, phonology.