* Real: If something is ostensible, it appears to be true but might not be. The opposite is real, meaning it is actually true.
* Actual: Similar to real, actual means something is genuinely what it appears to be.
* Genuine: Genuine implies something is authentic and not a facade.
* True: This is a general antonym, meaning the opposite of false or pretended.
* Hidden: Ostensible implies something is obvious, while hidden suggests it's concealed.
* Underlying: If something is ostensible, it's on the surface, while the underlying meaning is hidden.
* Secret: Similar to hidden, secret implies something is not meant to be known.
Example:
* Ostensible reason: The company's ostensible reason for the merger was to increase market share, but the real reason was to eliminate competition.
In this example, the antonyms of ostensible could be "real", "actual", or "true" depending on the emphasis.