pretentious or conspicuous show, as of wealth or importance; display intended to impress others.
Archaic. the act of showing or exhibiting; display.
Origin of ostentation
1425–75;late Middle Englishostentacioun < Middle Frenchostentation < Latinostentātiōn- (stem of ostentātiō), equivalent to ostentāt(us) past participle of ostentāre to display, exhibit, frequentative of ostendere to present, display (equivalent to os-, var of ob-ob- + ten(dere) to stretch + -t- frequentative suffix + -ātus-ate1) + -iōn--ion
mid-15c., from Old French ostentacion (mid-14c.) and directly from Latin ostentationem (nominative ostentatio) "showing, exhibition, vain display," noun of action from past participle stem of ostentare "to display," frequentative of ostendere "to show" (see ostensible).