Definition of “chaste” - English Dictionary. See all translations. uk ​ /tʃeɪst/ us ​ /tʃeɪst/ formal. › not having had sex, or only having a sexual relationship with the person you are married to: In the past, a woman needed to be chaste to make a good marriage. They exchanged a few chaste kisses (= not expressing sexual desire). › used to describe decoration or style that is very simple and smooth: