The word "un-genteel" implies a lack of refinement or polish. When looking for antonyms, we can consider words that convey sophistication, manners, and elegance. Among them are "cultivated," "gracious," "courteous," "polite," "well-mannered," "dignified," "civilized," and "gentlemanly." These antonyms suggest a level of refinement and decorum that contrasts with the uncouthness and rustiness of un-genteel. They suggest a sense of respect and courtesy that is lacking in un-genteel, which emphasizes the opposite of polite and refined behavior. Using these antonyms can help to create a positive tone in writing and speech, emphasizing the importance of manners and civilized behavior.