Impertinent (adjective)

1. Not relevant or appropriate to the situation; not pertinent.
2. Not showing proper respect; rude or insolent.
3. Overstepping the bounds of propriety; presumptuous.

Origin:

From the latin impertinentem (unsuitable, inappropriate), from in- (not) + pertinens (belonging to), from the verb pertinere (to pertain).

Examples:

1. His remark was impertinent and irrelevant to the discussion.
2. The salesperson's impertinent attitude made the customer uncomfortable.
3. It was impertinent of her to comment on my personal life.
4. The guest's impertinent behavior was not tolerated by the host.
5. His impertinent question caused the witness to lose her composure.