noun (common) (futsuumeishi)noun or participle which takes the aux. verb suruintransitive verbadjectival nouns or quasi-adjectives (keiyodoshi)nouns which may take the genitive case particle 'no'adultery;impropriety;(an) affair;immorality
隣の人が若い女の人と不倫しているらしいよ。
Did you hear that our neighbor was fooling around with a younger woman?