It's possible you're misremembering a term or a specific context. Could you please provide more information? For example:
* Where did you encounter this term? (e.g., a textbook, a lecture, a research paper)
* What is the general topic being discussed? (e.g., biology, genetics, evolution)
* Do you remember any other words or phrases associated with "merring"?
With more details, I can try to help you understand what you're looking for.