Source : Webster's Revised Unabridged Dictionary (1913)

Inconspicuous \In`con*spic"u*ous\, a. [L. inconspicuus. See
   {In-} not, and {Conspicuous}.]
   Not conspicuous or noticeable; hardly discernible. --
   {In`con*spic"u*ous*ly}, adv. -- {In`con*spic"u*ous*ness}, n.
   --Boyle.

Source : WordNet®

inconspicuousness
     n : the quality of being not easily seen [ant: {conspicuousness}]