noun, na-adjective, noun which may take the genitive case particle 'no'
unfaithfulness; infidelity; unchastity
Refers to sexual unfaithfulness in a committed relationship, especially marital infidelity. Often used in formal or literary contexts.
彼の不貞が原因で離婚した。
They divorced because of his infidelity.
不貞な行為は許されない。
Unfaithful acts are unforgivable.