IPA: /rɪˈzɛntfəli/
KK: /rɪˈzɛntfəlɪ/
In a way that shows anger or bitterness about something that is perceived as unfair or wrong.
She resentfully accepted the decision, even though she disagreed with it.
Resentfully → It is formed from "resent" (from Latin "sentire", meaning to feel) and "-ful" (meaning full of) and "-ly" (meaning in a manner). The word "resentfully" means in a manner that is full of resentment or feeling bitterness.
Think of feeling something deeply ('sentire') and being 'full of' that feeling ('-ful') — that's why resentfully means acting in a way that shows bitterness.