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halogen

American  
[hal-uh-juhn, -jen, hay-luh-] / ˈhæl ə dʒən, -ˌdʒɛn, ˈheɪ lə- /

noun

Chemistry.
  • halogens
    plural
  1. any of the electronegative elements, fluorine, chlorine, iodine, bromine, and astatine, that form binary salts by direct union with metals.


halogen British  
/ ˈhæləˌdʒɛn /

noun

  1. any of the chemical elements fluorine, chlorine, bromine, iodine, and astatine. They are all monovalent and readily form negative ions

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

halogen Scientific  
/ hăl′ə-jən /
  1. Any of a group of five nonmetallic elements with similar properties. The halogens are fluorine, chlorine, bromine, iodine, and astatine. Because they are missing an electron from their outermost shell, they react readily with most metals to form salts.

  2. See Periodic Table


Other Word Forms

Derived Forms

Inflected Forms

Nouns


Etymology

Origin of halogen

First recorded in 1835–45; halo- + -gen


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Explanation

A halogen is a chemical element that forms a salt when it reacts with metal. Halogen lamps are illuminated by bulbs that contain a halogen and an inert gas. There are five halogens in the periodic table of chemical elements: fluorine, chlorine, bromine, iodine, and astatine. The halogens are all highly reactive, which means they're quick to form bonds with other elements. What they often end up becoming is some kind of salt, including common table salt. In fact, the literal translation of halogen is "salt-producer," from Greek roots hals, "salt," and gen, "giving birth to."

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Vocabulary lists containing halogen

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

He did a more-than-competent job—he was Rossini after all—but the result always reminds me of shining a halogen light into a place of hallowed dim.

From The Wall Street Journal ● May 15, 2026

The study also shows that changing the type of halogen on the surface alters how MXenes interact with electromagnetic waves.

From Science Daily ● Apr. 4, 2026

One already well-understood source of glare is drivers retrofitting their vehicles, replacing old halogen bulbs with LEDs.

From BBC ● Oct. 27, 2025

The beam is whiter, more focused and brighter than the more diffuse light from halogen lamps fitted in older cars.

From BBC ● Oct. 27, 2025

As the broiling sun set, a different kind of American landscape lit up: The halogen floodlights from the truck stop could be seen for miles.

From "Geeks: How Two Lost Boys Rode the Internet Out of Idaho" by Jon Katz

By combining different halide salts, researchers created MXenes with two or even three types of surface halogens in carefully controlled proportions.

From Science Daily ● Apr. 4, 2026

Firstly, they are two to three times as bright as traditional halogens, and their "colour temperature" is bluer and whiter, which mimics natural daylight.

From BBC ● Feb. 18, 2026

Researchers also found that halogens interact with oil field emissions to form free radicals, which later become more stable compounds capable of traveling long distances.

From Science Daily ● Dec. 29, 2025

The metals of group 13 all react directly with nonmetals such as sulfur, phosphorus, and the halogens, forming binary compounds.

From Textbooks ● Feb. 14, 2019

Thus chlorine and the rest of the halogens, the atoms of which combine with one atom of hydrogen, are called univalent, oxygen a bivalent element, and so on.—ED.

From The New Physics and Its Evolution by Lucien Poincaré

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