curdle

American  

[kur-dl] / ˈkɜr dl /

verb (used with or without object)

curdled, curdling

1. to change into curd; coagulate; congeal.

2. to spoil; turn sour.

3. to go wrong; turn bad or fail.

   Their friendship began to curdle as soon as they became business rivals.

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idioms

1. curdle the / one's blood, to fill a person with horror or fear; terrify.

   a scream that curdled the blood.

curdle British  

/ ˈkɜːdəl /

verb

1. to turn or cause to turn into curd

2. to fill someone with fear

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Other Word Forms

• curdler noun
• noncurdling adjective
• uncurdled adjective
• uncurdling adjective

Etymology

Origin of curdle

First recorded in 1580–90; curd + -le

Explanation

When things curdle, they turn from liquid gradually to solid, forming clumps along the way. If you leave milk out of the refrigerator long enough, it will curdle. When a liquid curdles, it forms curds, or lumpy solid masses. In some cases this is deliberate, as when you make cheese or tofu. Other times, you might accidentally let something curdle, like a custard or sauce, or a forgotten container of cream at the back of your refrigerator. Curdle was originally crudle, from crud (later curd), "any coagulated substance," or "congeal."

Example Sentences

Piercing and horrible, the screaming is pitched to curdle the listener’s blood but not, in this instance, to overwhelm the voice of the narrator.

From The Wall Street Journal • Dec. 19, 2025

As co-written by Baumbach and Emily Mortimer, the reunion between the two former acting buddies starts warm but quickly begins to curdle.

From Los Angeles Times • Nov. 7, 2025

But just a couple of decades later, that optimism began to curdle.

From Salon • Apr. 27, 2025

Don’t be concerned if it starts to curdle — that’s normal.

From Washington Post • Sep. 2, 2022

From my place in the shade it isn’t so bad, but the stink of bodies, all sweating with the morning work, is enough to make milk curdle.

From "Red Queen" by Victoria Aveyard