Is it grammatically correct to say most preferable?

"Most preferable" is grammatically correct, but it's usually considered awkward and redundant.

Here's why:

* Preferable already implies a comparison and suggests something is more desirable than other options.

* Most implies a comparison between multiple options, which is already inherent in the word "preferable."

Instead of "most preferable," consider using:

* Most preferred (more common and natural)

* The most preferable (if you need to emphasize the superlative)

* Preferred (if the comparison is clear from context)

For example:

* Instead of: "This option is the most preferable."

* Try: "This option is the most preferred." or "This option is preferred."