IPA: /rɪˈmɔːrsfəli/
KK: /rɪˈmɔrsfəlɪ/
In a way that shows deep regret or guilt for a wrong action.
She looked at him remorsefully after realizing her mistake.
Remorsefully → It is formed from "re-" (meaning again) and "morsus" (from Latin, meaning to bite). The suffix "-fully" (meaning in a manner full of) indicates the manner of feeling. The word "remorsefully" means in a manner full of the feeling of biting regret or guilt again.
Think of feeling regret that 'bites' you again ('re-' means again and 'morsus' means to bite) — that's why remorsefully means feeling regret deeply.