monitor, any of various, mostly tropical lizards. A monitor lizard has a heavy body, long head and neck, long tail that comes to a whiplike end, and strong legs with sharp claws. Its slender, forked tongue is protrusible. Monitors range in size from the 8-in. (20-cm) short-tailed species of W Australia to the 10-ft, 300-lb (3-m, 136-kg) Komodo dragon, the giant among living lizards, that lives on the small Indonesian island of Komodo and some smaller neighboring islands. Some monitor species spend their lives in trees, and others inhabit lakes and rivers; they can be found on the oceanic islands and continents of the Eastern Hemisphere in all types of warm habitats, from tropical forest to desert. They feed on various kinds of animal matter, including eggs, rats, frogs, and decaying meat. The larger species will attack small deer and pigs. They often tear the prey with claws and teeth, but generally swallow it whole or in large chunks. Monitors lay from 7 to 35 leathery eggs, usually in holes in the ground or in trees. They are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Squamata, family Varanidae, genus Varanus.

monitor, type of turreted warship (no longer used) carrying heavy guns, having little draft, and lying low in the water. Monitors were so called from the first of the class, the Monitor, built for the Union navy in the U.S. Civil War by John Ericsson. Launched in Jan., 1862, the Monitor was 179 ft (55 m) long, of 41.5-ft (13-m) beam, and weighed 1,200 tons. A revolving turret, protected by 8 in. (20.3 cm) of iron armor and containing two 11-in. (27.9-cm) smooth-bore guns, was its main feature. The sides were covered by iron plates from 3 to 5 in. (7.6-12.7 cm) thick, with about 27 in. (69 cm) of wood backing, and the deck, only 18 in. (46 cm) above water, was shielded with 1-in. (2.54-cm) armor. The ship was moved by steam power, with a screw propeller. (See Monitor and Merrimack for more information.) Monitors were used extensively in the Civil War, but the type had limitations—it was too heavy to navigate the oceans—and was eventually abandoned. However, they were used by the British navy in World War I.

Any of about 50 species of lizards (genus Varanus, family Varanidae) found in the Old World tropics and subtropics. Most have an elongated head and neck, a heavy body, a long tail, and well-developed legs. The smallest monitor grows to 8 in. (20 cm), but several species (e.g., the Komodo dragon) are very large. The two-banded, or water, monitor (V. salvator) of Southeast Asia grows to 9 ft (2.7 m). The perentie (V. giganteus) of Australia grows to 8 ft (2.4 m). The earless monitor (Lanthanotus borneensis), a rare lizard of Borneo and the only species of the family Lanthanotidae, grows to 16 in. (40 cm) in length.

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Monitor may refer to:

Computers and technology

• Visual display unit, a device that displays images generated by a computer
• Monitor (synchronization), an approach to synchronize two or more computer tasks that use a shared resource
• Foldback (sound engineering), the use of rear-facing speakers on stage during a music performance
• Machine code monitor, software allowing users to view or change memory locations on a computer
• Medical monitor, automated medical device that senses and displays a patient's vital signs
• Studio monitor, a loudspeaker designed for audio production applications
• Supervisory control, a system that measures or controls data
• Video monitor, a device that displays output from a video-generating device
• Virtual Machine Monitor, software which virtualizes a computer hardware platform, allowing multiple system images to run simultaneously.

Warships

• Monitor (warship), a type of ship
• River monitor, a class of warship used in inland waterways
• USS Monitor, a United States Navy warship used during the American Civil War
• USS Monitor (LSV-5) a United States Navy vehicle landing ship

Companies Media and Entertainment

• Monitor (comics), a DC comics character
• Monitor (NBC Radio)
• Monitor (Polish newspaper)
• Monitor Magazine (Ottawa)
• Monitor Records (Hong Kong), a music retailer
• Monitor Records (New York), an independent record label
• Monitor Group, a strategy consulting firm
• 343 Guilty Spark, a character in the Halo video game
• Monitor (TV series), a BBC television programme from 1958 to 1965, edited by Huw Wheldon
• Monitor (record label) a former name of EMI Czech Republic record label

Place names

• Monitor, Indiana, a town in the United States
• Monitor, Oregon, an unincorporated community in the United States
• Monitor, Alberta, Canada

Other meanings

• Water jet used in hydraulic mining
• Fire monitor, a water jet used for firefighting
• Monitor (NHS), a United Kingdom government agency also known as the Independent Regulator for NHS Foundation Trusts
• Monitor lizard, a lizard
• Hall monitor, a student who supervises the corridors of a school

See also

• The Monitor
• The Monitors
• Monitoring