Also found in: Dictionary, Thesaurus, Medical, Legal, Acronyms, Idioms, Wikipedia.


common name for various unrelated invertebrate animals with soft, often long and slender bodies. Members of the phylum PlatyhelminthesPlatyhelminthes
, phylum containing about 20,000 species of soft-bodied, bilaterally symmetrical, invertebrate animals, commonly called flatworms. There are four classes: the free-living, primarily aquatic class, Turbellaria, and Trematoda, Cestoda, and Monogenea, which are
..... Click the link for more information.
, or the flatworms, are the most primitive; they are generally small and flat-bodied and include the free-living planariansplanarian,
common name for several genera of the free-living (turbellarian) flatworms belonging to the order Tricladida, a name that derives from their characteristic three-branched digestive cavities. Most species range from 1-8 in. to about 1 in. in length (.32–2.
..... Click the link for more information.
 (of the class Turbellaria) as well as the parasitic flukesfluke,
parasitic flatworm of the trematoda class, related to the tapeworm. Instead of the cilia, external sense organs, and epidermis of the free-living flatworms, adult flukes have sucking disks with which they cling to their hosts and an external cuticle that resists digestion
..... Click the link for more information.
 (class Trematoda) and tapewormstapeworm,
name for the parasitic flatworms forming the class Cestoda. All tapeworms spend the adult phase of their lives as parasites in the gut of a vertebrate animal (called the primary host).
..... Click the link for more information.
 (class Cestoda). The nemertines, or ribbon worms (phylum NemertineaNemertinea
, phylum of elongated, often flattened, marine Worms, sometimes called ribbon worms. There are 900 known species, ranging in size from a fraction of an inch to 90 ft (27 m).
..... Click the link for more information.
), are often colorful marine carnivores with an extensible proboscis. The smallest species are only a fraction of an inch (less than 2.5 cm) long, while giants of the group range up to 90 ft (27 m) and are the longest of all invertebrates. Pseuodcoelomate worms include those in the phyla RotiferaRotifera,
phylum of predominantly free-living, microscopic, aquatic or semiterrestrial pseudocoelomates. Each rotifer has a head bearing a crown of cilia, the corona, at the anterior end; most rotifers feed with the aid of currents generated by the coronal cilia.
..... Click the link for more information.
, Gastrotricha, KinorhynchaKinorhyncha
, phylum containing about 150 species of tiny pseudocoelomate worms, it is widely distributed in marine sediments. The kinorhynch body is divided into 13 segments, each covered with a cuticle and equipped with characteristic spines.
..... Click the link for more information.
, NematodaNematoda
, phylum consisting of about 12,000 known species, and many more predicted species, of worms (commonly known as roundworms or threadworms). Nematodes live in the soil and other terrestrial habitats as well as in freshwater and marine environments; some live on the deep
..... Click the link for more information.
, and NematomorphaNematomorpha
, small (about 230 species) phylum of pseudocoelomates; the horsehair worms. Most are very slender, elongated creatures found in ponds and streams, whose larvae live as parasites in arthropods. They emerge as adults for a brief time, then mate and die.
..... Click the link for more information.
. Of these, the largest phylum is the nematodes, which are probably the most numerous multicellular animals. Also called roundworms and threadworms, the nematodes include widespread free-living species as well as parasites, such as the hookwormhookworm,
any of a number of bloodsucking nematodes in the phylum Nematoda, order Strongiloidae that live as parasites in humans and other mammals and attach themselves to the host's intestines by means of hooks.
..... Click the link for more information.
. Other parasitic nematodes include Filaria, the cause of filariasis, which may result in elephantiasiselephantiasis
, abnormal enlargement of any part of the body due to obstruction of the lymphatic channels in the area (see lymphatic system), usually affecting the arms, legs, or external genitals.
..... Click the link for more information.
; Trichinella, the cause of trichinosistrichinosis
or trichiniasis
, parasitic disease caused by the roundworm Trichinella spiralis. It follows the eating of raw or inadequately cooked meat, especially pork.
..... Click the link for more information.
; Ascaris, an intestinal parasite of humans, horses, and pigs; the pinwormpinworm,
roundworm, Enterobius vermicularis, worldwide in distribution and the most common source of worm infestation of humans in the United States. Children are more commonly infested than adults.
..... Click the link for more information.
, a parasite common in children; the Guinea worm, Dracunculus medinensis, which is now restricted to a few N sub-Saharan African nations and is ingested as a larva in water and slowly emerges when full grown (up to 3 ft/91 cm) through a painful sore in the skin; and various other species that are agricultural pests. Like the nematodes, the hairworms, or horsehair worms, are unsegmented, but they are grouped separately in the phylum Nematomorpha. The larvae are parasitic, first in the bodies of aquatic insects and then within grasshoppers or beetles. The adult is about 6 in. (15 cm) long and covered with brown chitin, giving it a stiff appearance; since the worms were frequently found in watering troughs, superstition had it that they developed from horsehairs. The annelid worms (phylum AnnelidaAnnelida
[Lat., anellus=a ring], phylum of soft-bodied, bilaterally symmetrical (see symmetry, biological), segmented animals, known as the segmented, or annelid, worms.
..... Click the link for more information.
) have segmented bodies, distinct heads, digestive tubes, circulatory systems, and brains. Appendages on each segment are used for walking or swimming. They include the earthwormearthworm,
terrestrial, cylindrical segmented worm of the class Oligochaeta. There are 2,200 earthworm species, found all over the world except in arid and arctic regions and ranging in size from 1 in. (2.5 cm) to the 11-ft (330-cm) giant worms of the tropics.
..... Click the link for more information.
, of the class Oligochaeta, the leechleech,
predacious or parasitic annelid worm of the class Hirudinea, characterized by a cylindrical or slightly flattened body with suckers at either end for attaching to prey.
..... Click the link for more information.
 (class Hirudinea), and the marine annelids of the class Polychaeta. The sea mousesea mouse,
marine worm of the genus Aphrodite with a short, broad, segmented body, found in moderately deep water. The upper, or dorsal, surface of a sea mouse bears 15 pairs of raised scales; the space between the scales and the body surface forms a channel for the flow
..... Click the link for more information.
, the clam worm, and the feather duster worm belong to the latter group. The shipwormshipworm
or teredo
, marine bivalve mollusk of the family Teredinidae, specialized for boring in wood. A shipworm is not a worm, but a greatly elongated clam. Its two shells, enclosing only the front end of the body, function as a tool, rather than a protective
..... Click the link for more information.
 is a type of clam. The larvae of many insects are popularly called worms. Moth and butterfly larvae can be distinguished from adult animals called worms by the presence of several pairs of fleshy appendages at the rear end of the body (see caterpillarcaterpillar
, common name for the larva of a moth or butterfly. Caterpillars have distinct heads and are segmented and wormlike. They have three pairs of short, jointed legs (retained in the adult) on the thorax; in addition, they have unjointed, fleshy appendages, called
..... Click the link for more information.
). However, other insect larvae are completely legless, while still others are equipped with six pairs of legs, as in adult insects (see larvalarva,
independent, immature animal that undergoes a profound change, or metamorphosis, to assume the typical adult form. Larvae occur in almost all of the animal phyla; because most are tiny or microscopic, they are rarely seen. They play diverse roles in the lives of animals.
..... Click the link for more information.
). Insect larvae known as worms include the armywormarmyworm,
larva, or caterpillar, of a moth, Pseudaletia unipuncta or Mythimna unipuncta, found in North America E of the Rocky Mts.; also known as the common, or true, armyworm.
..... Click the link for more information.
, bagwormbagworm,
common name for the larva of small moths of the family Psychidae. The larva spins a silken cocoon as it travels, hence the term bagworm. When fully grown, the bagworm fastens its covering to a twig and pupates within it.
..... Click the link for more information.
, cutwormcutworm,
name for the larvae of many moths of the family Noctuidae (owlet moths). These larvae, or caterpillars, feed at night on the stems and roots of young plants, often cutting them off near the surface of the ground. They hide in soil by day.
..... Click the link for more information.
, and inchworminchworm,
name for the larvae of moths of the family Geometridae, a large, cosmopolitan group with over 1,200 species indigenous to North America. Also called measuring worms, spanworms, and loopers, inchworms lack appendages in the middle portion of their body, causing them to
..... Click the link for more information.

What does it mean when you dream about a worm?

The term worm is used metaphorically in some common English expressions to represent weakness and sneakiness, as in “he wormed his way into the group” or “what a worm he turned out to be.” The worm also symbolizes bait and rich, fertile soil.


(computer science)
A computer program that seeks to replicate itself and to spread, with the goal of consuming and exhausting computer resources, thereby causing computing systems to fail.
(design engineering)
A shank having at least one complete tooth (thread) around the pitch surface; the driver of a worm gear.
(invertebrate zoology)
The common name for members of the Annelida.
Any of various elongated, naked, soft-bodied animals resembling an earthworm.
Sweat of molten metal which exudes through the crust of solidifying metal in a casting, and is caused by gas evolution.


(computer science)
Pertaining to a storage device, such as an optical disk, that allows the user to record data only once and to read back the data an unlimited number of times. Abbreviation for write-one, read-many.


1. any of various invertebrates, esp the annelids (earthworms, etc.), nematodes (roundworms), and flatworms, having a slender elongated body
2. any of various insect larvae having an elongated body, such as the silkworm and wireworm
3. any of various unrelated animals that resemble annelids, nematodes, etc., such as the glow-worm and shipworm
4. a shaft on which a helical groove has been cut, as in a gear arrangement in which such a shaft meshes with a toothed wheel
5. a spiral pipe cooled by air or flowing water, used as a condenser in a still
6. a nontechnical name for lytta
7. Anatomy any wormlike organ, structure, or part, such as the middle lobe of the cerebellum (vermis cerebelli)
8. Computing a program that duplicates itself many times in a network and prevents its destruction. It often carries a logic bomb or virus


write once read many times: an optical disk that enables users to store data but not change it




(networking, security)
(From "Tapeworm" in John Brunner's novel "The Shockwave Rider", via XEROX PARC) A program that propagates itself over a network, reproducing itself as it goes. Compare virus. Nowadays the term has negative connotations, as it is assumed that only crackers write worms.

Perhaps the best-known example was the Great Worm.

Compare Trojan horse.


(1) A destructive program that replicates itself throughout a single computer or across a network, both wired and wireless. It can do damage by sheer reproduction, consuming internal disk and memory resources within a single computer or by exhausting network bandwidth. It can also deposit a Trojan that turns a computer into a zombie for spam and other malicious purposes. Very often, the terms "worm" and "virus" are used synonymously; however, worm implies an automatic method for reproducing itself in other computers. See virus, logic bomb, smartphone virus, Stuxnet, Worm.ExploreZip virus and Morris worm.

(2) A program that moves through a network and deposits information at each node for diagnostic purposes or causes idle computers to share some of the processing workload. See ethical worm.

(3) (WORM) (Write Once Read Many) An optical disc that can be recorded only once. Updating requires destroying the existing data (all 0s made 1s), and writing new data to an unused part of the disk.

There are two kinds of WORM technologies. Ablative large-format (12-14") WORM is the traditional type, which makes a permanent change in the optical material. Continuous composite write (CCW) WORM is a mode in multifunction 5.25" optical (MO) drives that emulates a WORM drive. The data are not permanently changed, but the drive contains firmware that ensures that recorded areas are not rewritten. See optical disc and MDISC.

WORM Cartridges
Large-format 12-14" WORM drives have used the ablative technology. Magneto-optic drives have firmware that turns MO media into write-once disks.


What thoughts come to mind when someone is called a worm? When we are dreaming about these animals, we may be reflecting on the more negative aspects of our own or someone else’s personality. Worms are usually associated with weakness and sneakiness. They are blind and generally feed on decaying matter. To associate these characteristics with any individuals, including yourself, indicates that you are seeing a very negative side of them and have a generally low opinion of them (or yourself). If you are dreaming about earthworms, the connotation is more positive because they make contributions to the general health of our environment. Old superstition-based dream interpretations say that dreaming about worms is a warning about poor health.
References in classic literature ?
They thought no more of the ugly worm, Who once had wakened their scorn; But looked and longed for the butterfly now, As the soft wind bore him on.
Dear flower," the butterfly whispered low, "Long hast thou waited for me; Now I am come, and my grateful love Shall brighten thy home for thee; Thou hast loved and cared for me, when alone, Hast watched o'er me long and well; And now will I strive to show the thanks The poor worm could not tell.
They were now very happy; their home was done, the four blue eggs lay in the soft nest, and the little wife sat still and patient on them, while the husband sang, and told her charming tales, and brought her sweet berries and little worms.
It is a great sacrifice for you lightloving Fairies to dwell through the long winter in the dark, cold earth, watching over the flowerroots, to keep them free from the little grubs and worms that seek to harm them.
One day, after he had borrowed The Worm's trap for a lady who never existed, had used it himself all the afternoon, had sent a note to The Worm purporting to come from the lady, and was telling the Mess all about it, The Worm rose in his place and said, in his quiet, ladylike voice: "That was a very pretty sell; but I'll lay you a month's pay to a month's pay when you get your step, that I work a sell on you that you'll remember for the rest of your days, and the Regiment after you when you're dead or broke.
Two months passed, and the Senior Subaltern still educated The Worm, who began to move about a little more as the hot weather came on.
The Senior Subaltern was so pleased with getting his Company and his acceptance at the same time that he forgot to bother The Worm.
One night, at the beginning of the hot weather, all the Mess, except The Worm, who had gone to his own room to write Home letters, were sitting on the platform outside the Mess House.
But the woman had fled through a door, and on the paper was written:--"This is to certify that I, The Worm, have paid in full my debts to the Senior Subaltern, and, further, that the Senior Subaltern is my debtor, by agreement on the 23d of February, as by the Mess attested, to the extent of one month's Captain's pay, in the lawful currency of the India Empire.
The "Shikarris" made him President of the Regimental Dramatic Club; and, when the Senior Subaltern paid up his debt, which he did at once, The Worm sank the money in scenery and dresses.
The Global Worm Gear Industry Report 2015 is a professional and in-depth study on the current state of the worm gear industry.
The worm gearings with axis not parallel and not concurrent are in the main cases reducing gears that mean that the worm is the motor element.