fluorine

noun

fluo·​rine ˈflu̇r-ˌēn 

ˈflȯr-

: a nonmetallic gaseous chemical element of the halogen group with atomic number 9 that readily forms compounds with almost all other elements including some noble gases see Chemical Elements Table

Examples of fluorine in a Sentence

Recent Examples on the Web

The researchers also flagged some samples with small traces of fluorine, a chemical that can lead to lower birth rates in high doses, as well as organohalogens and nitroaromatics—both known to have carcinogenic effects. —Aude Konan, Scientific American, 11 Feb. 2026

By introducing fluorine to the borate crystal framework and carefully controlling the structure, the team outlined a broader design strategy for discovering future vacuum ultraviolet nonlinear optical materials. —Georgina Jedikovska, Interesting Engineering, 4 Feb. 2026

Teflon, for example, the brand name for a type of polymer made up of carbon and fluorine, is commonly used in cookware because its low reactivity makes the material non-stick. —Isabella Backman, Hartford Courant, 27 Jan. 2026

Some of the substances used in two-phase immersion cooling largely contain fluorine and carbon, which help create types of per- and polyfluoroalkyl chemicals (PFAS). —Molly Taft, Wired News, 26 Nov. 2025

Word History

Etymology

French, from New Latin fluor

First Known Use

1813, in the meaning defined above

Rhymes for fluorine

• agin
• alkene
• allene
• ameen
• amin
• amine
• arene
• athene
• baleen
• beeline
• benzene
• between

Kids Definition

fluorine

noun

flu·​o·​rine

ˈflu̇(-ə)r-ˌēn, 

-ən

: a nonmetallic element that is normally found alone as a pale yellowish flammable irritating poisonous gas having two atoms per molecule see element

Medical Definition

fluorine

noun

fluo·​rine ˈflu̇(-ə)r-ˌēn  -ən 

: a nonmetallic monovalent halogen element that is normally a pale yellowish flammable irritating toxic gas

—symbol F see Chemical Elements Table