The antonyms for the word "un-authorized" are "authorized," "approved," "licensed," "legitimate," and "official." An authorized person or action is one that is officially permitted or endowed with the necessary power to act. An approved action is one that has been specifically allowed or given the go-ahead by an appropriate authority. Similarly, a licensed action is one that has been granted permission by a regulatory body or government agency. A legitimate action is one that is in accordance with established laws or regulations. An official action is one that is carried out by a duly constituted authority or organization. In summary, antonyms for "unauthorized" are words that suggest legality, legitimacy, and official sanction.