Synonyms for onset Found 4 synonyms across 2 meanings for “onset”. the beginning or early stages (noun) oncoming (military) an offensive against an enemy (using weapons) (noun) attackonslaughtonrush Explore Related Words Rhymes with onsetSynonyms for oncomingSynonyms for attackSynonyms for onslaughtSynonyms for onrush Synonym Finder | Rhyme Finder | Poetry Editor