un·der·age /ˌʌndərˈeɪdʒ◂/ adjectiveadj PGCtoo young to legally buy alcohol, drive a car, vote etc 未成年的,未及法定年龄的 underage• They also express concern about the addiction and underage gambling they believe will be the inevitable partners of online gambling.• Tilden died broke, and shunned by many because of his conviction for homosexuality with underage partners.