If you describe a person's behaviour or remarks as unbecoming, you mean that they are shocking and unsuitable for that person. His conduct was totally unbecoming to an officer in the British armed services Those involved had performed acts unbecoming of university students
not in keeping with accepted standards of what is right or proper in polite society; "was buried with indecent haste"; "indecorous behavior"; "language unbecoming to a lady"; "unseemly to use profanity"; "moved to curb their untoward ribaldry"