Emily Dickinson Lexicon

LAS'SI-TUDE, n. [Fr. from L. lassitudo, from lassus, and this from laxus, laxo, to relax.]

1. Weakness; dullness; heaviness; weariness; languor of body or mind, proceeding from exhaustion of strength by excessive labor or action, or other means.
2. Among physicians, lassitude is a morbid sensation of languor which often precedes disease.