Surly, a. [Compar. Surlier; superl. Surliest.]
Etymology: [Probably from sir, and originally meaning, sirlike, i.e., proud. See Sir, and Like, a.]
1. Arrogant; haughty. [Obs.] Cotgrave.
2. Gloomily morose; ill-natured, abrupt, and rude; severe; sour; crabbed; rough; sullen; gloomy; as, a surly groom; a surly dog; surly language; a surly look. "That surly spirit, melancholy." Shak.
3. Rough; dark; tempestuous. Now softened into joy the surly storm. Thomson.
Shades of meaning
Fernald has no entry of its own for surly; he lists it under morose.
Where he writes about it:
A surly person is in a state of latent anger, resenting approach as intrusion, and ready to take offense at anything; thus we speak of a surly dog. — from morose
Sullen and sulky moods may be transitory; one who is morose or surly is commonly so by disposition or habit. — from morose