Origin: 1425–75; late ME ostentacioun < MF ostentation < L ostentātiōn- (s. of ostentātiō), equiv. to ostentāt(us) ptp. of ostentāre to display, exhibit, freq. of ostendere to present, display (equiv. to os-, var of ob-ob-+ ten(dere) to stretch + -t- freq. suffix + -ātus-ate1) + -iōn--ion
Pretentious display meant to impress others; boastful showiness.
Archaic The act or an instance of showing; an exhibition.
[Middle English ostentacioun, from Old French ostentacion, from Latin ostentātiō, ostentātiōn-, from ostentāre, frequentative of ostendere, to show; see ostensible.]
1436, from M.Fr. ostentation (1366), from L. ostentationem (nom. ostentatio) "vain display," from ostentatus, pp. of ostentare "to display," freq. of ostendere (see ostensible).