It's possible you're thinking of a different prefix, or you might be encountering it in a specific context where it has a unique meaning. Could you provide more information about how you encountered the word "ling"? For example:
* What word is the prefix attached to?
* What is the context of the word?
* Where did you see/hear the word?
With more information, I can help you understand the meaning of "ling" in your specific situation.