not faithful, in particular 不诚实的;不忠的: 尤指 ■engaging in sexual relations with a person other than one's regular partner in contravention of a previous promise or understanding 不信守婚誓的;通奸的 you haven't been unfaithful to him, have you?. 你没有对他不忠,对吗。 her unfaithful husband. 她有婚外恋的丈夫。 ■disloyal, treacherous, or insincere 不忠实的;不守信的;不诚实的 she felt that to sell the house would be unfaithful to her parents' memory. 她觉得卖房子是对已故父母的不忠。