Pompous, a. — Webster enters it under “pompous”
Etymology: [F. pompeux, L. pomposus. See Pomp.]
1. Displaying pomp; stately; showy with grandeur; magnificent; as, a pompous procession.
2. Ostentatious; pretentious; boastful; vainlorious; as, pompous manners; a pompous style. "Pompous in high presumption." Chaucer. he pompous vanity of the old schoolmistress. Thackeray. -- Pom"ous*ly, adv. -- Pomp"ous*ness, n.
Shades of meaning
Fernald has no entry of its own for pompousness; he lists it under ostentation.
Where he writes about it:
Pomposity and pompousness are the affectation of pomp. — from ostentation