whey

American  

[hwey, wey] / ʰweɪ, weɪ /

noun

1. a milk serum, separating as liquid from the curd after coagulation, as in cheesemaking.

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whey British  

/ weɪ /

noun

1. the watery liquid that separates from the curd when the milk is clotted, as in making cheese

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Other Word Forms

• wheyey adjective
• wheylike adjective

Etymology

Origin of whey

First recorded before 900; Middle English whei(e), whai(e), wei, Old English hwæg, hwæig, hwǣg, hweg; cognate with Dutch, Low German wei

Explanation

Whey is what's left over after you've made cheese by straining curds. Rather than being thrown away, whey is often used to add buttery flavor or extra protein to processed foods. You may know the word whey from the nursery rhyme that begins "Little Miss Muffet sat on her tuffet eating her curds and whey..." Curds and whey are part of the cheese-making process, with whey being the slightly sour leftover liquid. Think buttermilk or thin yogurt, and you've got an idea of what whey tastes like. It's actually a great source of protein and often shows up in healthy smoothies and shakes.

Example Sentences

Executive producers Jon Erwin and Jon Gunn discuss bringing the biblical character to life in their series and whey they cast Michael Iskander in the lead role.

From Los Angeles Times • Mar. 20, 2026

The protein trend has been especially driven by the expanded availability of protein from whey, typically a by-product of cheese production.

From BBC • Oct. 6, 2025

He adds: "When I started my career, people used to talk about whey protein just as a supplement to your diet. Now the number of companies putting protein on anything and everything is insane."

From BBC • May 11, 2025

But there were barriers to using whey themselves by a range of things, from the set-up cost of a new facility to the challenge of scale, competing priorities and the distance to potential partners.

From Salon • Oct. 22, 2024

“You wouldn’t starve to death on Ma’s whey, like old Grimes did on his wife’s,” Pa said.

From "Little House in the Big Woods" by Laura Ingalls Wilder