PFAS GUIDE

What Does PFAS Stand For?

Q: What does PFAS stand for?

PFAS stands for per- and polyfluoroalkyl substances, a class of thousands of synthetic chemicals built around chains of carbon atoms bonded to fluorine.

Q: How is PFAS pronounced?

PFAS is commonly pronounced 'PEE-fass.' Some speakers spell out the letters, but the single-word pronunciation is most common in news coverage.

Q: What is the difference between per- and poly-fluoroalkyl?

In perfluoroalkyl substances, every carbon in the chain is fully bonded to fluorine. In polyfluoroalkyl substances, at least one carbon is fluorinated but not all of them. Both fall under the PFAS umbrella.

By David Meldofsky, California-licensed attorney · Founder, Lawsuit Informer

Last updated: June 2, 2026

PFAS stands for per- and polyfluoroalkyl substances. It is not a single chemical but an umbrella term for a class of thousands of synthetic chemicals — by some counts more than 12,000 — that share a backbone of carbon atoms bonded to fluorine. That carbon-fluorine bond is what makes them so durable, and so persistent in the environment.

This page breaks down the name itself, how it is pronounced, and the difference between the "per-" and "poly-" forms. For the full overview, start with What Are PFAS (Forever Chemicals)?

This page provides general educational information only and does not constitute medical or legal advice.

Key Takeaways:

PFAS = per- and polyfluoroalkyl substances.
It describes a whole class of chemicals, not one compound.
The shared feature is a carbon-fluorine chain, the source of their durability.
It is usually pronounced "PEE-fass."

Breaking Down the Name

The acronym describes the chemistry. "Fluoroalkyl" refers to an alkyl chain — a string of carbon atoms — that carries fluorine. The prefix tells you how much:

Perfluoroalkyl: every carbon in the chain is fully saturated with fluorine.
Polyfluoroalkyl: at least one carbon is fluorinated, but not all of them.

Both groups are grouped together under "PFAS" because they behave similarly in the environment and the body.

Why a Class, Not a Single Chemical

When a news report says a product "contains PFAS," it is describing membership in a large family rather than one specific substance. Two items can both contain PFAS while involving entirely different compounds — which is part of why regulating and litigating PFAS is complex. Two of the most studied members are PFOA and PFOS; see PFAS vs. PFOA vs. PFOS Explained.

How Is PFAS Pronounced?

Most people say "PEE-fass" as a single word. You will also hear the letters spelled out, but the one-word pronunciation dominates in coverage and in courtrooms.

Common Questions