per·fi·dy /ˈpɜːfɪdɪ/ n. 〈书〉背信弃义(行为)；不忠贞(行为) an act of perfidy 背信弃义的行为 the perfidy of one's lover 情人的负心 All his perfidies have not gone unnoticed. 他全部的背叛行径人们并非没有注意。 The name of Judas has become a byword of covetousness and perfidy. 犹大的名字已成了贪婪与背叛的代名词。 [<L perfidia < perfidus faithless < PER-+ fidēs faith]