say it: aw-sten-TAY-shuhn
ostentation is a noun meaning "a gaudy outward display". It carries 3 recorded senses.
lack of elegance as a consequence of being pompous and puffed up with vanity
pretentious or showy or vulgar display
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for ostentation come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.