His rude behavior demeaned his image in the eyes of his colleagues.

demeaned 是动词 demean 的过去式。demean 由前缀 de-（表示"向下、降低"）和词根 mean（"低劣的、卑贱的"）组成，字面意思是"使...显得卑贱"，引申为"贬低、降低...的身份或尊严"。