halogen

American  

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

noun

Chemistry.

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

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halogen British  

/ ˈhæləˌdʒɛn, həˈlɒdʒɪnəs /

noun

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

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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

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Other Word Forms

• halogenoid adjective
• halogenous adjective

Etymology

Origin of halogen

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

Compare meaning

How does halogen compare to similar and commonly confused words? Explore the most common comparisons:

• halide vs. halogen

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."

Example Sentences

Another problem is the illegal retrofitting of LED bulbs, especially when fitted into units designed for halogen.

From BBC • Feb. 18, 2026

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

When illuminated by the microscope's halogen lamp and analyzed through a spectrometer, the light separates into different wavelengths.

From Science Daily • Oct. 23, 2025

When a simple halogen lamp illuminates the tiny cavities, the light inside is captured as if in a trap.

From Science Daily • Oct. 23, 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

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