Emily Dickinson Lexicon

MO-ROSE, a. [L. morosus; It. and Sp. moroso, slow, tardy. In Portuguese, moroso signifies dwelling on lewd thoughts; morosidade, the act of dwelling on such thoughts. Morose then is from the root of L. moror, to delay, stop, hinder, whence commoror, to dwell, Fr. demeurer, Eng. demur. The customary sense then is derived from the gloomy, sullen temper formed by habitually fixing the thoughts on some object.]

Of a sour temper; severe; sullen and austere. Some have deserved censure for a morose and affected taciturnity; others have made speeches though they had nothing to say. Watts.