The term BE RESENTFUL can be defined by three crossword solutions: MOPE (4 letters), SULK (4 letters), and STEW (4 letters). MOPE is to feel or show a lack of energy or enthusiasm. SULK is to be in a bad mood, often as a result of feeling hurt or disappointed. Lastly, STEW is to feel or show anger or annoyance over something that has happened. All three words describe the feeling of being resentful, which is to feel bitter or indignant about something.