Here are some synonyms for "ostensibly":
* Apparently
* Seemingly
* On the surface
* Superficially
* In appearance
* outwardly
Example:
"Ostensibly, he was a successful businessman, but in reality, he was deeply in debt."
In this example, the businessman appears to be successful, but the reality is different. The word "ostensibly" highlights the discrepancy between appearances and reality.