the action or state of being unfaithful to a spouse or other sexual partner (对配偶或性伙伴的)不忠行为;不忠 her infidelity continued after her marriage. 她婚后仍有不忠行为。 [count noun]I ought not to have tolerated his infidelities. 我当初不应容忍他的不忠行为。
disbelief in a particular religion, especially Christianity 不信奉宗教(尤指基督教)
语源
late Middle English (in the senses 'lack of faith' and 'disloyalty'): from Old French infidelite or Latin infidelitas, from infidelis 'not faithful' (see infidel)