PFOS

abbreviation or noun

ˌpē-ˌef-ˌō-ˈes How to pronounce PFOS (audio)
: a fluorinated sulfonic acid C8HF17O3S that is a member of the PFAS group and that has been used especially for its water and stain resistance (as in carpeting and food packaging) and as a surfactant (as in firefighting foam and alkaline cleaners) : perfluorooctanesulfonic acid
By 2002, the primary U.S. manufacturer of PFOS had voluntarily phased out its production because it was found in human populations and in wildlife.—National Association for Surface Finishing
In addition, private parties that clean up releases of PFOS and PFOA could now recover cleanup costs from potentially responsible parties.—Stephanie Salmon

called also perfluorooctane sulfonate

Examples of PFOS in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Levels of forever chemicals Two forever chemicals, PFOA and PFOS, deserve attention first. — Christine Kirchhoff, The Conversation, 30 July 2026 Previous research by the same team indicated that elevated levels of PFOA and PFOS also were connected to other childhood cancers, including acute myeloid leukemia and Wilms tumor. — Rachel Fobar, Oc Register, 1 May 2026 This isn’t surprising to me, as short-chain PFAS are known to absorb more efficiently into plants than long-chain PFAS like PFOS. — Sarah Todd, STAT, 1 May 2026 Several foam samples had individual forever chemicals present at more than one million parts-per-trillion, including perfluorooctane sulfonic acid (PFOS) — one of six PFAS explicitly regulated by the EPA. — Peter Aitken, MSNBC Newsweek, 27 Sep. 2025 See All Example Sentences for PFOS

Word History

First Known Use

2002, in the meaning defined above

Time Traveler
The first known use of PFOS was in 2002

Browse Nearby Words

Pforzheim
PFOS
pfp
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Cite this Entry

“PFOS.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/PFOS. Accessed 5 Aug. 2026.

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