Extraneousness refers to something that is unrelated, irrelevant, or unnecessary in a particular context. Antonyms for the word extraneousness include relevance, importance, and significance. These words indicate that something is crucial or vital to a given situation or task. Another antonym for extraneousness is applicability, which implies that something is appropriate and suitable for the intended purpose. Pertinence is yet another antonym, and it suggests that something is relevant and closely related to the matter at hand. In short, antonyms for extraneousness all connote the opposite of something that is peripheral or irrelevant, and instead indicate that something is pertinent, valuable or necessary.