Churn
Old English cyrin, of Germanic origin; related to Middle Low German kerne and Old Norse kirna .
wiktionary
Noun from Middle English cherne, chrine, chyrne, kyrne ( > Scots kirn), from Old English ċyrn, ċyrin, ċirin(“churn”), from Proto-Germanic *kernǭ(“churn”); verb from Middle English chernen from Old English ċernan, from Proto-Germanic *kirnijaną(“to churn, stir”), of unknown origin. Cognate with West Frisian tsjerne, Dutch karn, Walloon serene, German Karn, Kirne, Danish kjærne, Swedish kärna, Icelandic kirna.
etymonline
churn (n.)
"vessel in which cream or milk is agitated to separate it and make butter," Old English cyrin, from Proto-Germanic *kernjon (source also of Old Norse kirna, Swedish kärna, Danish kjerne, Dutch karn, Middle High German kern); probably akin to cyrnel "kernel" (see kernel) and describing the "grainy" appearance of churned cream.
churn (v.)
mid-15c., chyrnen, "to stir or agitate (milk or cream) to make butter," from churn (n.). Extended sense "shake or agitate violently" is from late 17c. Intransitive sense is from 1735. Related: Churned; churning. To churn out, of writing, "produce mechanically and in great volume" is from 1902.