Other forms: curdled, curdling, curdles
To curdle is to separate into lumps, as sour milk does. The milk curdled, curdle the sauce, made his blood curdle.
It happens when the protein clumps, and acid or heat will both do it — which is why lemon in warm milk separates and why a sauce splits if it boils. Blood-curdling is a fixed phrase for anything terrifying enough to be worth the exaggeration.
1verbcurdleTo separate into lumps, as sour milk does.
“If you let the sauce boil, the cream will curdle and go lumpy.”
curdle is a separating.
From curd, an older form crudle, meaning to form into curds.
Middle English
curd
English
curd
English, today
curdle
Built from
of earlier dialectal cruddle, crudle, equivalent to curd + le. curd comes from Middle English curd, a metathetic variant of crud, crudde (“coagulated substance”). a doublet of crud.
Etymology from Wiktionary, CC BY-SA