IPA: /ɪmˈpɛnɪtənt/
KK: /ɪmˈpɛnɪtənt/
Not feeling or showing regret for one's actions; unrepentant.
Despite his mistakes, he remained impenitent and refused to apologize.
Impenitent → It is formed from "in-" (meaning not) and "paenitens" (from Latin, meaning feeling regret or remorse). The word describes someone who does not feel regret or remorse for their actions.
Think of someone who is 'not' ('in-') feeling 'remorse' ('paenitens') for their actions — that's what impenitent means.