The Collaborative International Dictionary of English v.0.48:

Morose \Mo*rose"\ (m[-o]*r[=o]s"), a. [L. morosus, prop.,
   excessively addicted to any particular way or habit, fr. mos,
   moris, manner, habit, way of life: cf. F. morose.]
   1. Of a sour temper; sullen and austere; ill-humored; severe.
      "A morose and affected taciturnity." --I. Watts.
      [1913 Webster]

   2. Lascivious; brooding over evil thoughts. [Obs.]
      [1913 Webster]

   Syn: Sullen; gruff; severe; austere; gloomy; crabbed; crusty;
        churlish; surly; ill-humored.
        [1913 Webster]

WordNet (r) 3.0 (2006):

morose
    adj 1: showing a brooding ill humor; "a dark scowl"; "the
           proverbially dour New England Puritan"; "a glum, hopeless
           shrug"; "he sat in moody silence"; "a morose and
           unsociable manner"; "a saturnine, almost misanthropic
           young genius"- Bruce Bliven; "a sour temper"; "a sullen
           crowd" [syn: dark, dour, glowering, glum,
           moody, morose, saturnine, sour, sullen]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "morose":
   autistic, bashful, beetle-browed, black, black-browed, brooding,
   broody, brusque, chapfallen, choleric, close, crabbed, cranky,
   crestfallen, dark, dejected, dissociable, dour, dumpish, frowning,
   gloomy, glowering, glum, grim, gruff, grum, incompatible,
   insociable, irascible, irritable, long-faced, lowering, melancholy,
   moodish, moody, mopey, moping, mopish, mumpish, nongregarious,
   saturnine, scowling, self-contained, self-sufficient, sick, sickly,
   snug, socially incompatible, splenetic, sulky, sullen, surly,
   testy, ugly, unclubbable, uncommunicative, uncompanionable,
   uncongenial, unfriendly, ungenial, unsociable, unsocial, waspish