Lassitude(n.) A condition of the body, or mind, when its voluntary functions are performed with difficulty, and only by a strong exertion of the will; languor; debility; weariness.
Thesaurus Entries
acedia, adynamia, anemia, apathy, atony, blah feeling, bloodlessness, blues, boredom, brain fag, cachexia, cachexy, cowardice, debilitation, debility, depression, disinterest, disregard, doldrums, drowsiness, dullness, dumps, enervation, enfeeblement, ennui, etiolation, exhaustion, eyestrain, faintness, fatigue, feebleness, flabbiness, flaccidity, goneness, heart strain, heaviness, hebetude, heedlessness, impotence, inanimation, indifference, insouciance, jadedness, lackadaisicalness, languidness, languishment, languor, languorousness, lenitude, lentor, lethargy, lifelessness, listlessness, mental fatigue, mental strain, oscitancy, overstrain, overtiredness, passivity, phlegm, powerlessness, prostration, satedness, sleep, sleepiness, sloth, slothfulness, slowness, sluggishness, slumber, softness, somnolence, stance fatigue, strain, strengthlessness, stupefaction, stupor, supineness, tedium, tiredness, torpidity, torpidness, torpitude, torpor, unconcern, unmindfulness, weakliness, weakness, wearifulness, weariness, world-weariness