accidental 3 antonyms and opposites of accidental. Adj — Happening by chance rather than on purpose. Synonyms for accidental circumstantial incidental casual contingent occasional fortuitous serendipitous accidentary by accident by the by causeless chanceable lippening random unforeseen unintended unintentional unplanned Antonyms for accidental inevitable intentional impossible ← Back to the full definition of accidental
