The direct opposite of “polite” is typically “impolite” or “rude.” If you’re exploring nuance, context can shift the most natural antonym:

• impolite: not showing good manners or consideration.
• rude: deliberately disrespectful or insensitive.
• discourteous: lacking courtesy or manners in a way that is socially frowned upon.

For teaching or vocabulary work, these shades help distinguish degrees of offense:

• Polite vs impolite: basic contrast in manners.
• Courteous vs discourteous: focus on consideration and respect in interactions.
• Respectful vs disrespectful: broader emphasis on regard toward others.