Synonyms:
* Showy: This is a general synonym for ostentatious, meaning something that is designed to attract attention.
* Flamboyant: This implies a more dramatic and colorful style.
* Brash: This suggests a boldness that might be considered excessive or rude.
* Gaudy: This refers to something that is excessively bright and showy, often considered tasteless.
* Pretentious: This emphasizes a desire to appear impressive, often in a way that is insincere.
* Conspicuous: This means something that is easily noticed or attracting attention.
* Grandiose: This refers to something that is impressive in scale or scope, but can also be seen as excessive or pompous.
Antonyms:
* Unassuming: This means being modest and not seeking attention.
* Subdued: This implies a quiet, restrained style.
* Simple: This suggests something that is plain and unadorned.
* Modest: This refers to something that is not extravagant or showy.
* Humble: This implies a lack of pride or arrogance.
The best synonym or antonym to use will depend on the specific context and the nuance you want to convey.