[1] : The Collaborative International Dictionary of English v.0.48

lassitude \las"situde\ la^s"si^t=ud, n. l. lassitudo,
   fr. lassus faint, weary; akin to e. late: cf. f. lassitude.
   see late.
   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.
   1913 webster

         the corporeal instruments of action being strained to a
         high pitch . . . will soon feel a lassitude. --barrow.
   1913 webster
see also:
late 

[2] : WordNet (r) 2.0

lassitude
     n 1: a state of comatose torpor as found in sleeping sickness
          syn: lethargy, sluggishness
     2: a feeling of lack of interest or energy syn: languor, listlessness
     3: weakness characterized by a lack of vitality or energy syn:
         inanition, lethargy
see also:
lethargy sluggishness languor listlessness inanition 

[3] : Moby Thesaurus II by Grady Ward, 1.0

91 moby thesaurus words for "lassitude":
   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

Lassitude >> L Words
Lassitude, definition of term: Lassitude
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