The crossword solution for the term SHOW OSTENTATIOUSLY is FLOURISH. To FLOURISH means to grow or develop in a healthy or vigorous way, especially as the result of a particularly favorable environment. It can also mean to be successful or prosperous, or to display something in an exaggerated or ostentatious manner. In this case, the term SHOW OSTENTATIOUSLY is referring to the latter definition, suggesting that someone is displaying something in an overly showy or grandiose way.