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(nā`päm), incendiary material developed during World War II by Harvard scientists cooperating with the U.S. army and used in bombs and flame throwers. Napalm is based on a mixture of gasoline, sometimes mixed with other petroleum fuels, and a thickening agent. The thickener, to which the term napalm was originally applied, turns the mixture into a thick jelly that flows under pressure, as when shot from a flame thrower, and sticks to a target as it burns. One of the first thickeners used was an aluminum soap (a salt of aluminum and certain fatty acids). Later thickeners have been based on polystyrene and similar polymers.


See R. M. Neer, Napalm: An American Biography (2013).

The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a combustible product used as an incendiary and flame-thrower mixture. It is produced by adding a special powder thickening agent, consisting of a mixture of aluminum salts of organic acids such as naphthenic and palmitic acids, to a combustible liquid (gasoline, kerosine, or other petroleum products). For gasoline the quantity of thickening agent is 4—11 percent of the weight of the fuel, and the consistency of the napalm varies from a viscous liquid to an almost solid jelly.

Napalm ignites easily, burns slowly, giving off thick, pungent black smoke (the temperature of the flame is 900°-1100°C, depending on the type of fuel), and adheres well to targets, including vertical surfaces. A new napalm (napalm B), which even sticks to moist surfaces, has been developed in the USA on the basis of polystyrene. If magnesium and inorganic oxidants are added to napalm, the flame temperature of the resulting incendiary mixture rises to 1600°C. The cinders that form during combustion can burn through metal elements. If alloys of light metals are added, the mixture self-ignites on the target, especially when the target is wet or covered with snow. Such mixtures are called supernapalms and cannot be extinguished with water.

Napalm is used in aerial bombs, flame traps, portable and mechanized flame-throwers, and incendiary antipersonnel cartridges, and for destruction of combat materiel. It is also used to cause fires. Napalm was adopted by the US Army in 1942 and was used by American aviation during World War II (1939–45), the war of aggression against the Korean people in 1950–53, and, on a particularly broad scale, in the aggression against Vietnam from 1964 to 1973.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


Aluminum soap in powder form, used to gelatinize oil or gasoline for use in napalm bombs or flame throwers.
The resultant gelatinized substance.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


An incendiary substance that contains naphthenic and palmitic acids and gasoline. The acids, on contact with each other, produce very high temperatures, and the gasoline tends to stick to the surfaces. The other contents of napalm can be powdered aluminum and soap or a similar compound used to gelatinize oil or gasoline. The mixture is put into a container and dropped from an aircraft. The troops in trenches suffer not only from burns caused by the flowing gasoline but other casualties result from the sudden shortage of oxygen, which is consumed by the sudden and intense fires caused by the intense burning.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved


a thick and highly incendiary liquid, usually consisting of petrol gelled with aluminium soaps, used in firebombs, flame-throwers, etc.
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005