What type of word is an exclamation or interruption?

An exclamation or interruption is categorized as an interjection. Interjections are words or phrases that express strong emotions or sudden bursts of feeling, often standing alone or positioned at the beginning of a sentence. Examples include words like "wow!" or "ouch!" which signal a reaction or emotional response.

Interjections can add emphasis or convey the speaker's mood, making them distinct from other parts of speech. For instance, they do not typically serve grammatical functions within sentences like nouns, pronouns, or adverbs do. Instead, they function primarily to convey emotion or reaction, which is why they are identified as a separate category.