IPA: //ʌn.rɪˈpɛn.tənt//
KK: /ʌnˈrɛpɪntənt/
Not feeling sorry or guilty about something wrong that one has done.
Despite the evidence against him, he remained unrepentant about his actions.
Unrepentant → It is formed from "un-" (meaning not) and "repent" (from Latin "paenitere", meaning to feel regret or sorrow). The word describes someone who does not feel regret or remorse for their actions.
Think of someone who is 'not' ('un-') feeling 'sorrow' ('paenitere') for what they have done — that's why unrepentant means lacking remorse.