* A misspelling of a similar word, such as "prosaic," "prosematic," or "prognostic."
* A technical term used in a specific field. If you have context for where you encountered the word, please provide it so we can determine its meaning.
* A made-up word. It's possible the word was invented for a fictional context, like a book or game.
If you can provide more information, I can help you figure out the meaning of "proismatic."