Entry 1 sense Webster, 1913 Ostentatious /äsˌ-tən-tāsh'-əs/ · Os·ten·ta·tious · IPA /ˌɒs.tɛnˈteɪ.ʃəs/ 01 a. Fond of, or evincing, ostentation; unduly conspicuous; pretentious; boastful. 1. Fond of, or evincing, ostentation; unduly conspicuous; pretentious; boastful. “Far from being ostentatious of the good you do.” — Dryden. “The ostentatious professions of many years.” — Macaulay.