The word "worm" (vermis) is a generic term used for insects and other invertebrates, as well as worms. The Latin word vermis is the source for the English word "vermin". In medieval manuscripts most invertebrates were called "worms".

The worm is born without intercourse from flesh, wood or earth, though it is sometimes born from an egg. Worms inhabit the earth, water, air, flesh, wood, leaves, or clothing.