WordNet (r) 3.0 (2006):

blahs
    n 1: a general feeling of boredom and dissatisfaction

Moby Thesaurus II by Grady Ward, 1.0:

97 Moby Thesaurus words for "blahs":
   acedia, aloofness, angst, anguish, anxiety, apathy, ataraxia,
   ataraxy, benumbedness, blah, blue devils, blues, boredom,
   cheerlessness, comatoseness, detachment, discomfort, discomposure,
   discontent, disinterest, dislike, dismals, dispassion, displeasure,
   disquiet, dissatisfaction, doldrums, dolefuls, dread, dullness,
   dumps, emptiness, ennui, existential woe, flatness, grimness,
   heartlessness, hebetude, hopelessness, inappetence, indifference,
   inquietude, insouciance, joylessness, lack of appetite,
   lack of pleasure, languidness, lethargicalness, lethargy,
   listlessness, malaise, megrims, mopes, mulligrubs, mumps, nausea,
   nonchalance, nongratification, nonsatisfaction, numbness,
   painfulness, passiveness, passivity, phlegm, phlegmaticalness,
   phlegmaticness, plucklessness, resignation, resignedness,
   savorlessness, sloth, sluggishness, sopor, soporifousness,
   spiritlessness, spleen, spunklessness, staleness, stupefaction,
   stupor, sulks, supineness, tastelessness, tediousness, tedium,
   torpidity, torpidness, torpor, uncomfortableness, unconcern,
   unease, uneasiness, unhappiness, unpleasure, unsatisfaction,
   vexation of spirit, withdrawnness