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

The wiping cloth sanitizing solution was just water — zero parts per million chlorine sanitizer. —David J. Neal, Miami Herald, 27 Feb. 2026

The combination creates a toxic chlorine gas that can be extremely dangerous when exposed. —Kait Hanson, Southern Living, 26 Feb. 2026

Still, most swimmers and divers prefer being in an outdoor pool because of conditions connected with the chlorine residue of indoor pools. —Bill Center, San Diego Union-Tribune, 25 Feb. 2026

If there is mold in your humidifier, it should be deep cleaned with either chlorine bleach or hydrogen peroxide—never both together. —Mary Marlowe Leverette, The Spruce, 25 Feb. 2026

Word History

First Known Use

1810, in the meaning defined above

Phrases Containing chlorine

• chlorine dioxide
• chlorine monoxide

Rhymes for chlorine

• organochlorine

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