If you could provide more context, like where you saw or heard this word, I might be able to help you figure out what it's supposed to mean.
For example:
* Did you see it in a text message or online? Maybe it's a typo for a real word, like "government" or "management".
* Was it spoken? It might be a slang term or a regional dialect word that I'm not familiar with.
Please provide more details so I can help you understand what "mernment" might mean.