adj.不忠实的;不正直的;(翻译等)不可靠的;不贞洁的;
例句:
He has never been unfaithful to his wife.
他从未封妻子不忠过.
He was an unfaithful lover.
他真是个薄情郎.
He is unfaithful to his duty.
他不忠于职守.