Worm

A worm is any of numerous relatively small elongated soft-bodied invertebrate animals. The most famous is the Earthworm, a member of phylum Annelida, but there are hundreds of thousands of different species that live in a wide variety of habitats other than soil.

Originally, the word referred to any creeping or a crawling animal of any kind or size, such as a serpent, caterpillar, snail, or the like. Later this definition was narrowed to the modern definition which still includes several different animal groups. Some of these are from the phyla; Annelida, Chaetognatha, Nematoda (“roundworms”), Nemertea and Platyhelminthes (“flatworms”). Many insect larvae are also called “worms”.

Worm is a nordic word for a dragon (also spelled "Wyrm").

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In computer science, a worm is a self-replicating computer program, similar to a virus, except that the virus attaches to other programs and the worm does not.