Buttermilk is the sour liquid left after churning butter. A glass of buttermilk, buttermilk pancakes, marinate in buttermilk.
Its acidity does two useful things: it reacts with bicarbonate of soda to raise a batter, and it tenderises chicken without turning it to mush. What is sold now is usually cultured milk rather than the true by-product. The name says exactly what it is.
1nounbuttermilkThe sour liquid left after churning butter.
“Soak the chicken in buttermilk before frying it.”
buttermilk is a liquid.
Butter plus milk, recorded in Middle English. The word names the milk left when butter is churned out of cream.
Middle English
butter-melke
English, today
buttermilk
Middle English butter-melke, equivalent to butter + milk. Cognate with Dutch botermelk (“buttermilk”), German Buttermilch (“buttermilk”), Low German Bottermelk (“buttermilk”), lb Bottermëllech (“buttermilk”), pdt Bottamalkj, Bottamaltj, Bottermalkj, Bottermaltj (“buttermilk”), and Yiddish פּוטערמילך, פּוטער־מילעך (“buttermilk”).
Etymology from Wiktionary, CC BY-SA