MOPE (4 letters) The term 'be sullen' can be described by two crossword solutions: 'POUT' and 'MOPE'. Pouting is a facial expression that conveys displeasure, displeasure, or displeasure. It is usually done by pressing the lips together and frowning. Moping is a behavior that expresses sadness, depression, or boredom. It is often characterized by a lack of energy and motivation. Both pouting and moping are expressions of being sullen, which is defined as having a gloomy or bad-tempered attitude.