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 work focuses on FLiBe, a molten salt made of fluorine, lithium, and beryllium that is considered one of the leading materials for producing and extracting tritium inside future fusion reactors. — Neetika Walter, Interesting Engineering, 8 July 2026

This week, the EPA approved pesticides that contain molecules with carbon-fluorine bonds, which can be very strong and therefore difficult to break down over time. — Rachel Frazin, The Hill, 1 July 2026

In 2025, French firm Veolia flexed its global leadership in PFAS treatment by opening a massive plant in Delaware that filters PFAS from water and incinerates it to break the bond between fluorine and carbon, one of the strongest in chemistry. — Don Steinberg, Time, 30 Apr. 2026

The front glass also includes an anti-smudge coating, fluorine, a material that repels grease and moisture. — Jim Fisher, PC Magazine, 16 Mar. 2026

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
• arene
• athene
• baleen
• beeline
• benzene
• between
• bromine

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