IPA: /ɪmˈpɜːrtɪnənt/
KK: /ɪmˈpɜrtənənt/
Rude or disrespectful, especially in a way that is not appropriate or polite.
The child's impertinent remarks shocked the adults at the dinner table.
Impertinent is formed from "im-" (meaning not) and "pertinere" (meaning to pertain or relate). The word describes behavior that does not pertain to the matter at hand, often implying rudeness or disrespect.
Think of 'not pertaining' ('im-') to the situation — that's why impertinent describes someone who is rude or irrelevant.