surly \SUR-lee\ (adjective) - 1 : Ill-humored; churlish in manner or mood; sullen and gruff. 2 : Menacing or threatening in appearance, as of weather conditions; ominous.

"A large surly- looking human in sunbleached khakis and a military cap stood facing them, impressive arms folded across his equally impressive chest." -- Sean Williams, Shane Dix, 'Force Heretic - Reunion'

Surly is from Middle English sirly, "lordly," from sir, "lord," which eventually came to mean "arrogant or haughty," whence the more negative modern sense.