unbecoming
adjective uk/ˌʌn.bɪˈkʌm.ɪŋ/ us/ˌʌn.bɪˈkʌm.ɪŋ/
formal（衣着）不合身的，不相配的，难看的
Unbecoming clothes do not look attractive on a particular person.
（行为）不恰当的，不得体的，不可接受的
Unbecoming behaviour is not correct or not acceptable.
He was charged with conduct unbecoming (to) an officer. 他被控行为有失军官身份。