Source : Webster's Revised Unabridged Dictionary (1913)

Ostentatious \Os`ten*ta"tious\, a.
   Fond of, or evincing, ostentation; unduly conspicuous;
   pretentious; boastful.

         Far from being ostentatious of the good you do.
                                                  --Dryden.

         The ostentatious professions of many years. --Macaulay.
   -- {Os`ten*ta"tious*ly}, adv. -- {Os`ten*ta"tious*ness}, n.

Source : WordNet®

ostentatiousness
     n : lack of elegance as a consequence of being pompous and
         puffed up with vanity [syn: {ostentation}, {pomposity}, {pompousness},
          {pretentiousness}, {splashiness}, {inflation}]