ETYM Latin morosus, prop., excessively addicted to any particular way or habit, from mos, moris, manner, habit, way of life: cf. French morose.
1. Of a sour temper; sullen and austere; ill-humored; severe.
2. Brooding over evil thoughts.

ETYM Old Eng. solein, solain, lonely, sullen; through Old French from (assumed) Late Lat. solanus solitary, from Latin solus alone. Related to Sole.
1. Gloomily angry and silent; cross; sour; affected with ill humor; morose.
2. Lonely; solitary; desolate.
3. Gloomy; dismal; foreboding.