Source : Webster's Revised Unabridged Dictionary (1913)

Inapt \In*apt"\, a. [Pref. in- not + apt: cf. F. inapte. Cf.
   {Inept}.]
   Unapt; not apt; unsuitable; inept. -- {In*apt"ly}, adv. --
   {In*apt"ness}, n.

Source : WordNet®

inaptness
     n : in appropriateness; "greater inaptness of expression would
         be hard to imagine" [syn: {inappositeness}] [ant: {aptness},
          {aptness}]