churn -- (stir (cream) vigorously in order to make butter)
churn, boil, moil, roil -- (be agitated; "the sea was churning in the storm")
Overview of adj churning
The adj churning has 2 senses
churning, churned-up -- (moving with or producing or produced by vigorous agitation; "winds whipped the piled leaves into churning masses"; "a car stuck in the churned-up mud")
churning, roiling, roiled, roily, turbulent -- ((of a liquid) agitated vigorously; in a state of turbulence; "the river's roiling current"; "turbulent rapids")