The Collaborative International Dictionary of English v.0.48:

Infelicity \In`fe*lic"i*ty\, n.; pl. Infelicities. [L.
   infelicitas: cf. F. inf['e]licit['e]. See In- not, and
   Felicity.]
   [1913 Webster]
   1. The state or quality of being infelicitous; unhappiness;
      misery; wretchedness; misfortune; lack of suitableness or
      appropriateness. --I. Watts.
      [1913 Webster]

            Whatever is the ignorance and infelicity of the
            present state, we were made wise and happy.
                                                  --Glanvill.
      [1913 Webster]

   2. That (as an act, word, expression, etc.) which is
      infelicitous; as, infelicities of speech.
      [1913 Webster]

WordNet (r) 3.0 (2006):

infelicity
    n 1: inappropriate and unpleasing manner or style (especially
         manner or style of expression) [ant: felicitousness,
         felicity]

Moby Thesaurus II by Grady Ward, 1.0:

143 Moby Thesaurus words for "infelicity":
   Gothicism, abnormality, aching heart, agony, agony of mind,
   anguish, anomaly, antiphrasis, bad taste, bale, barbarism,
   barbarousness, bitterness, bleeding heart, bombasticness,
   broken heart, cacology, cacophony, cheerlessness, clumsiness,
   coarseness, corruption, crudeness, crushing, cumbrousness,
   depression, depth of misery, desolation, despair, discontent,
   displeasure, dysphemism, extremity, futility, gracelessness, grief,
   grimness, grossness, harshness, heartache, heaviness, heavy heart,
   humorlessness, ill-balanced sentences, impoliticalness,
   impoliticness, impropriety, impurity, inadmissibility,
   inadvisability, inapplicability, inappositeness, inappropriateness,
   inaptitude, inaptness, inauspiciousness, inconcinnity, incongruity,
   inconvenience, inconveniency, incorrectness, indecorousness,
   inelegance, inelegancy, ineptitude, inexpedience, inexpediency,
   infestivity, inopportuneness, inopportunity, intempestivity,
   interruption, intrusion, irrelevance, irrelevancy, joylessness,
   lack of finish, lack of polish, lateness, leadenness,
   maladjustment, malapropism, melancholia, melancholy, mesalliance,
   mirthlessness, misalliance, misconstruction, misery, misjoinder,
   misjoining, mismatch, missaying, misusage, pompousness,
   ponderousness, poor diction, prematurity, prostration, roughness,
   rudeness, sadness, sesquipedalianism, sesquipedality,
   slipshod construction, solecism, stiltedness, suicidal despair,
   tastelessness, turgidity, uncheerfulness, uncongeniality,
   uncouthness, undesirability, uneuphoniousness, unfavorableness,
   unfitness, unfittingness, unfortunateness, ungracefulness,
   ungrammaticism, unhappiness, unjoyfulness, unmeetness,
   unmirthfulness, unprofitability, unprofitableness,
   unpropitiousness, unrefinement, unripeness, unseasonableness,
   unseemliness, unsuitability, untimeliness, unwieldiness,
   unwiseness, uselessness, vulgarism, vulgarity, woe, worthlessness,
   wretchedness, wrongness