unfaithful /ˌʌnˈfeɪθfəl/ adjective Learner's definition of UNFAITHFUL
1
: having a sexual relationship with someone who is not your wife, husband, or partner不忠的;有通奸行爲的 —
often + to 2
: not accurate不確切的;不準確的 —
often + to
— unfaithfulness
noun [noncount]