chlorine

noun

chlo·​rine ˈklȯr-ˌēn 

-ən

: a halogen element that is isolated as a heavy greenish-yellow diatomic gas of pungent odor and is used especially as a bleach, oxidizing agent, and disinfectant in water purification see Chemical Elements Table

Examples of chlorine in a Sentence

Recent Examples on the Web

If water remains stagnant in a reservoir, there is a risk that chloramine, the chemical used as a disinfectant, will break down and chlorine will evaporate, leaving behind ammonia that could foster bacterial growth in the water supply. —Matt Hamilton, Los Angeles Times, 10 Jan. 2025

The three-compartment sink’s chlorine sanitzer didn’t measure up to standards. —David J. Neal, Miami Herald, 8 Jan. 2025

Adding chlorine to organic compounds helps create the building blocks of a number of important materials, including pharmaceuticals. —Alex Knapp, Forbes, 3 Jan. 2025

Close the drain tightly with a plug to prevent chlorine fumes from escaping. —Daley Quinn, Southern Living, 19 Dec. 2024

Word History

First Known Use

1810, in the meaning defined above

Phrases Containing chlorine

• chlorine dioxide
• chlorine monoxide

Kids Definition

chlorine

noun

chlo·​rine ˈklō(ə)r-ˌēn 

ˈklȯ(ə)r-,

-ən

: a nonmetallic element that is found alone as a heavy greenish yellow irritating gas having two atoms per molecule and a strong odor and that is used especially as a bleach, oxidizing agent, and disinfectant in water purification see element

Medical Definition

chlorine

noun

chlo·​rine ˈklō(ə)r-ˌēn, ˈklȯ(ə)r-, -ən 

: a halogen element that is isolated as a heavy greenish yellow gas of pungent odor and is used especially as a bleach, oxidizing agent, and disinfectant in water purification

—symbol Cl see Chemical Elements Table