impertinent

Impertinent describes behavior or remarks that overstep appropriate boundaries—rude in a presumptuous way: Don't be impertinent with your elders.

An impertinent question pries where it shouldn't or challenges authority inappropriately.

The word carries an old-fashioned ring, suggesting the speaker holds traditional views about respect and deference.

Less commonly, impertinent means irrelevant to the matter at hand: The judge struck the impertinent testimony from the record.