os ‧ ten ‧ ta ‧ tion /ˌɒstənˈteɪʃ ə n, -ten- $ ˌɑː-/ BrE AmE noun [uncountable] formal
[ Date: 1400-1500 ; Language: Old French ; Origin: Latin , from ostentare 'to show ostentatiously' , from ostendere ; ⇨ ↑ ostensible ]
when you deliberately try to show people how rich or clever you are, in order to make them admire you:
Her lifestyle was remarkably free from ostentation.