Definition of worm

• any of numerous relatively small elongated soft-bodied animals especially of the phyla Annelida and Chaetognatha and Nematoda and Nemertea and Platyhelminthes; also many insect larvae
• a person who has a nasty or unethical character undeserving of respect
• a software program capable of reproducing itself that can spread from one computer to the next over a network; "worms take advantage of automatic file sending and receiving features found on many computers"