Ostentatiously is an adverb used to describe a behavior that is meant to impress others. When looking for synonyms, one could use words like conspicuously, showily, flamboyantly, or extravagantly. These words convey the idea of an over-the-top or exaggerated behavior aimed at garnering attention. Other possible synonyms include pompously, grandiosely, and pretentiously, which have a slightly negative connotation and imply a certain degree of arrogance or self-importance. Additionally, some more nuanced synonyms could include theatrically, dramatically, and ceremoniously, which suggest a more intentional and deliberate effort to put on a show.