* It's a misspelling: Perhaps you meant a similar word like "messy," "mess," or "resume."
* It's a slang term: It could be a slang term used in a specific community or region.
* It's a fictional word: Maybe it's a made-up word from a book, movie, or game.
To understand the meaning, please provide more context:
* Where did you encounter the word? (e.g., a book, a conversation, a website)
* What was the surrounding text or conversation?
With more information, I can help you figure out what "messumo" might mean.