defining traits
- characteristicDistinguishing quality or trait
- distinctiveReadily identifiable, set apart
- signatureHandwritten name for verification
- hallmarkDistinguishing characteristic or mark
- quintessentialRepresenting the ideal type
unique · identifying · telltale · unmistakable · personality · essence · core · innate · inherent · nature · quirks · fingerprint · marker · stamp · brand · quality · attribute · peculiar