'Morose' means sullen, ill-tempered, or gloomy in demeanor. A morose person is characterized by a gloomy, surly, or bad-tempered disposition. 'Gloomy' is the most accurate synonym among the options, directly capturing the sullen, dark, or depressed aspect of moroseness. 'Ill' typically means sick, 'Calm' means peaceful, and 'Diseased' refers to having a medical condition.