fluoride

American  

[floor-ahyd, flawr-, flohr-] / ˈflʊər aɪd, ˈflɔr-, ˈfloʊr- /

noun

Chemistry.

1. a salt of hydrofluoric acid consisting of two elements, one of which is fluorine, as sodium fluoride, NaF.

2. a compound containing fluorine, as methyl fluoride, CH 3 F.

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fluoride British  

/ ˈflʊəˌraɪd /

noun

1. any salt of hydrofluoric acid, containing the fluoride ion, F ^–

2. any compound containing fluorine, such as methyl fluoride

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fluoride Scientific  

/ flr′īd′ /

1. A compound containing fluorine and another element or radical. Fluorine combines readily with nearly all the other elements, except the noble gases, to form fluorides. In some countries, fluoride is added to the drinking water as a preventive measure against tooth decay.

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fluoride Cultural  

1. Any of a number of naturally occurring compounds of the element fluorine. Fluorides have been found to be effective in preventing tooth decay and are routinely added to drinking water in most jurisdictions.

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Etymology

Origin of fluoride

First recorded in 1820–30; fluor- + -ide ( def. )

Compare meaning

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

• fluorine vs. fluoride

Explanation

Fluoride is that ingredient in toothpaste that keeps tooth enamel strong and helps prevent cavities. Small amounts of fluoride are also present in tap water and certain foods and beverages. Fluoride is a naturally occurring mineral widely recognized for its oral health benefits. Fluoride is often added to toothpaste and mouthwash to help prevent tooth decay by making the enamel more resistant to acid attacks from bacteria and sugars. That’s why some communities add it to their water supply systems: Regular exposure to fluoride is generally considered important in maintaining oral hygiene. Fluoride is also found in tea, seafood, and some fruits and vegetables. Now that’s toothsome!

Example Sentences

Kairos uses molten fluoride salt as a coolant, allowing it to operate at low pressures and high temperatures, and it also has a smaller demonstration reactor under construction in Oak Ridge.

From The Wall Street Journal • Apr. 23, 2026

“However, this is still not likely as there was at least some sodium fluoride which would help preserve the sample.”

From Los Angeles Times • Mar. 19, 2026

The Health Secretary has also used his bully pulpit to attack products he views as toxins, including pesticides and fluoride in water.

From The Wall Street Journal • Jan. 7, 2026

Existing treatments like fluoride varnishes and remineralization products can help relieve symptoms but do not actually rebuild enamel.

From Science Daily • Nov. 6, 2025

My fluoride theory is pretty much out the window.

From "Linked" by Gordon Korman