Ungentlemanly (adjective)

Not having the qualities considered appropriate for a gentleman; impolite; rude; discourteous.

Origin:

From un- (not) + gentlemanly (having the qualities considered appropriate for a gentleman).

Examples:

1. He was acting in an ungentlemanly way, and so the lady didn't want to dance with him.
2. His behavior was ungentlemanly, and so the host asked him to leave the party.
3. His words were ungentlemanly, and so the judge decided to punish him.
4. His attitude was ungentlemanly, and so the customer decided to complain.
5. His conduct was ungentlemanly, and so the teacher decided to expel him.