Definition of sullen

• a. - Lonely; solitary; desolate.
• a. - Gloomy; dismal; foreboding.
• a. - Mischievous; malignant; unpropitious.
• a. - Gloomily angry and silent; cross; sour; affected with ill humor; morose.
• a. - Obstinate; intractable.
• a. - Heavy; dull; sluggish.
• n. - One who is solitary, or lives alone; a hermit.
• n. - Sullen feelings or manners; sulks; moroseness; as, to have the sullens.
• v. t. - To make sullen or sluggish.