Lo ‧ tha ‧ ri ‧ o /ləˈθɑːriəʊ $ ləʊˈθeə ə -/ BrE AmE noun [countable]
a man whose main interest is in having sex with as many women as possible without having a serious relationship with any of them. Lothario is a character in Nicholas Rowe's play The Fair Penitent (1703) who persuades a woman to have sex with him, but is later disloyal to her:
the office Lothario