The word "un-gentlemanly" implies behavior that is inappropriate for a gentleman or someone who displays good manners and conduct. Some antonyms for "un-gentlemanly" include gentlemanly, courteous, polite, chivalrous, professional, respectful, dignified, refined, considerate, and well-behaved. These words describe individuals who demonstrate good character and display a high level of decency in their actions and speech. By contrast, those who exhibit behavior that is "un-gentlemanly" are often perceived negatively and may be seen as lacking in appropriate social skills and respect for others. Antonyms for "un-gentlemanly" therefore describe the opposite kind of behavior - one that is appropriate and respectful of others.