The Collaborative International Dictionary of English v.0.48:

Malaise \Ma`laise"\, n. [F., fr. mal ill + aise ease.] (Med.)
   An indefinite feeling of uneasiness, or of being sick or ill
   at ease.
   [1913 Webster]

WordNet (r) 3.0 (2006):

malaise
    n 1: physical discomfort (as mild sickness or depression) [syn:
         malaise, unease, uneasiness]

Moby Thesaurus II by Grady Ward, 1.0:

241 Moby Thesaurus words for "malaise":
   Schmerz, Slough of Despond, abnormality, aches and pains,
   acute disease, affection, affliction, agitation, ailment,
   all-overs, allergic disease, allergy, angst, anguish, anxiety,
   anxiety hysteria, anxiety neurosis, anxious bench, anxious concern,
   anxious seat, anxiousness, apprehension, apprehensiveness, atrophy,
   bacterial disease, birth defect, blank despondency, blight,
   bluster, bobbery, boil, boiling, boredom, brouhaha, bustle,
   cankerworm of care, cardiovascular disease, care, cheerlessness,
   chronic disease, churn, circulatory disease, commotion, complaint,
   complication, concern, concernment, condition, congenital defect,
   conturbation, death wish, debility, decrepitude, defect,
   deficiency disease, deformity, degenerative disease, dejectedness,
   dejection, depression, despair, despondency, despondentness,
   disability, discomfort, discomposure, discontent, discouragement,
   disease, disheartenment, dislike, disorder, dispiritedness,
   displeasure, disquiet, disquietude, dissatisfaction, distemper,
   distress, disturbance, dolor, down trip, downcastness, downer,
   downheartedness, dread, drooping spirits, dullness, ebullition,
   embroilment, emptiness, endemic, endemic disease,
   endocrine disease, ennui, epidemic disease, excitement,
   existential woe, fear, feebleness, ferment, fermentation, fever,
   feverishness, fidgets, flap, flatness, flurry, fluster,
   flutteration, foment, foreboding, forebodingness, fume,
   functional disease, fungus disease, fuss, gastrointestinal disease,
   genetic disease, grimness, handicap, heartlessness,
   hereditary disease, hopelessness, hubbub, hurly-burly, hurt,
   hurting, iatrogenic disease, illness, indisposition,
   infectious disease, infirmity, inquietude, jitters, joylessness,
   jumpiness, lack of pleasure, low spirits, lowness,
   lowness of spirit, maelstrom, malady, misery, misgiving, moil,
   morbidity, morbus, muscular disease, nausea, nerviness, nervosity,
   nervous strain, nervous tension, nervousness, neurological disease,
   nongratification, nonsatisfaction, nutritional disease,
   occupational disease, oppression, organic disease, overanxiety,
   pain, painfulness, pandemic disease, pathological condition,
   pathology, perturbation, pessimism, pins and needles,
   plant disease, protozoan disease, psychosomatic disease, pucker,
   respiratory disease, restlessness, rockiness, roil, rout, row,
   savorlessness, secondary disease, seediness, seethe, seething,
   self-destructive urge, sickishness, sickliness, sickness, signs,
   sinking heart, solicitude, spiritlessness, spleen, staleness, stew,
   stir, strain, suffering, suicidal despair, suspense, swirl,
   symptomatology, symptomology, symptoms, syndrome, taedium vitae,
   tastelessness, tediousness, tedium, tension, the pip, to-do,
   trepidation, trepidity, trouble, tumult, tumultuation, turbidity,
   turbulence, turmoil, twitter, uncomfortableness, unease,
   uneasiness, unhappiness, unhealthiness, unpleasure, unquietness,
   unrest, unsatisfaction, upset, urogenital disease, vexation,
   vexation of spirit, virus disease, wasting disease,
   weariness of life, worm disease, zeal