* A misspelling: Perhaps you meant a similar-sounding word like "Dementia" or "Demetrius".
* A personal name: It could be a unique name, possibly of a specific culture or origin.
* A fictional term: It might appear in a book, game, or other work of fiction.
Could you provide more context? Where did you encounter the word "Demita"? Knowing the source might help determine its meaning.