The word "un-chaster" refers to someone or something that is not pure or modest. Some synonyms for this word include impure, lascivious, immoral, and promiscuous. These words all suggest a lack of moral restraint or a disregard for societal norms regarding sexual behavior. Other synonyms for "un-chaster" might include wanton, licentious, debauched, or hedonistic. These words all convey a sense of excess or indulgence in physical pleasures, without regard for the potential consequences. Whether used to describe a person or an act, these synonyms for "un-chaster" all suggest a lack of purity or moral virtue.