The Collaborative International Dictionary of English v.0.48:

Inappropriate \In`ap*pro"pri*ate\, a.
   Not instrument (to); not appropriate; unbecoming; unsuitable;
   not specially fitted; -- followed by to or for. --
   In`ap*pro"pri*ate*ly, adv. -- In`ap*pro"pri*ate*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inappropriateness
    n 1: inappropriate conduct [syn: inappropriateness,
         wrongness] [ant: appropriateness, rightness]
    2: the quality of being not particularly suitable or befitting;
       "he retracted nothing that he had said about the
       inappropriateness of either a corporeal God or a God who is a
       person"; "his praise released from her loud protestations of
       her unworthiness" [syn: inappropriateness, unworthiness]
       [ant: appropriateness]

Moby Thesaurus II by Grady Ward, 1.0:

114 Moby Thesaurus words for "inappropriateness":
   Babbittry, aberrance, aberrancy, abnormality, anomaly, bad taste,
   bourgeois taste, camp, campiness, criminality, delinquency,
   deviance, deviancy, disentitlement, empty claim, empty title,
   excess, false claim, futility, high camp, illegality,
   impoliticalness, impoliticness, improperness, impropriety,
   inadmissibility, inadvisability, inapplicability, inappositeness,
   inaptitude, inaptness, inauspiciousness, incongruity,
   inconvenience, inconveniency, incorrectness, indecency,
   indecorousness, indecorum, indelicacy, indiscreetness,
   indiscretion, inelegance, inelegancy, ineptitude, inexpedience,
   inexpediency, infelicity, infraction, inopportuneness,
   inopportunity, intempestivity, interruption, intrusion,
   invalid claim, irrelevance, irrelevancy, kitsch, lack of claim,
   lateness, low camp, maladjustment, mesalliance, misalliance,
   misjoinder, misjoining, mismatch, no claim, philistinism,
   poor taste, pop, pop culture, prematurity, sinfulness,
   tastelessness, unaestheticism, unaestheticness, unbecomingness,
   unchastity, uncongeniality, undeservedness, undeservingness,
   undesirability, undueness, unentitledness, unfavorableness,
   unfitness, unfittingness, unfortunateness, unlawfulness,
   unmeetness, unmeritedness, unprofitability, unprofitableness,
   unpropitiousness, unrighteousness, unripeness, unseasonableness,
   unseemliness, unsuitability, unsuitableness, untimeliness,
   unwiseness, uselessness, violation, vulgar taste, vulgarism,
   vulgarity, vulgarness, wickedness, worthlessness, wrong,
   wrongfulness, wrongness