means The larva of the moth Bombyx mori, which spins a cocoon of fine fiber that humans unwind into silk thread.

from A plain compound of "silk" and "worm," both Old English (seolc and wyrm). "Worm" once meant almost any creeping or crawling creature — including caterpillars, snakes, even dragons — so a "silk-worm" was simply the small crawling thing that made silk. "Silk" itself likely traveled the trade routes back from the East; many trace it ultimately to a name for the Chinese (compare Latin Sericum and Greek Sēres, "the silk people").