When something is described as "razor-thin", it means that it is incredibly thin, almost to the point of being sharp. However, if you're looking for alternative words to describe this same concept, there are a few options. "Wafer-thin" is one possibility, suggesting that the item is as thin as a wafer or cracker. "Paper-thin" is another option, conjuring up images of paper that is so thin, it is almost transparent. You could also use "fine" or "delicate" to describe something that is razor-thin, or even "ultra-thin" if you want to emphasize just how thin it is. Whatever word you choose, it's clear that "razor-thin" conveys just how incredibly thin something is.