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.

---

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

---

Other Word Forms

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

Etymology

Origin of curdle

First recorded in 1580–90; curd + -le

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

Pro tip: Greek yogurt tends to curdle in hot applications, so it's best to reserve it for room temperature or chilled recipes.

From Salon • Sep. 3, 2022

This kind of comparison can curdle people’s relationships to one another — and to their own jobs.

From New York Times • Feb. 15, 2022

By now she understood that the mood in the nursery had begun to curdle, so to speak, and that the cause had something to do with her shutting of the windows.

From "The Unseen Guest" by Maryrose Wood