It's possible you are thinking of:
* "רענדערן" (rendern): This is the Yiddish verb meaning "to render" in the sense of "to melt down fat" or "to extract fat from something". It can also be used more generally to mean "to make, produce, or create something".
* "רענדערן" (rendern) can also be used in the sense of "to translate", particularly when referring to the translation of a text from one language to another.
* "רענדער" (renderer): This word can be used to refer to a person who renders fat or to a person who translates something.
If you can provide more context or an example sentence where you encountered this word, I might be able to give you a more precise translation.