sullen

Etymology

From Middle English solein, from Anglo-Norman soleyn (“alone”), from Old French sole (“single, sole, alone”), from Latin sōlus (“by oneself alone”). The change in meaning from "single" to morose occurred in Middle English.

adj

1. Having a brooding ill temper; sulky.
   And sullen I forsook the imperfect feast. 1709, Matthew Prior, Pleasure
   2007, Steven Wilson, "Normal", Porcupine Tree, Nil Recurring. Sullen and bored the kids stay / And in this way wish away each day
2. Gloomy; dismal; foreboding.
   a sullen atmosphere
3. Sluggish; slow.
4. (obsolete) Lonely; solitary; desolate.
5. (obsolete) Mischievous; malignant; unpropitious.
6. (obsolete) Obstinate; intractable.
   Things are as sullen as we are. a. 1694, John Tillotson, Imprudence of Atheism

noun

1. (obsolete) One who is solitary, or lives alone; a hermit.
2. (in the plural) Sullen feelings or manners; sulks; moroseness.