The Collaborative International Dictionary of English v.0.48:

Churn \Churn\, v. t. [imp. & p. p. Churned (ch[^u]rnd); p. pr.
   & vb. n. Churning.] [OE. chernen, AS. cernan; akin to LG.
   karnen, G. kernen, D. karnen, Dan. kierne, Sw. k[aum]rna, and
   also to E. corn, kernel, the meaning coming from the idea of
   extracting the kernel or marrow. See Kernel.]
   1. To stir, beat, or agitate, as milk or cream in a churn, in
      order to make butter.
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   2. To shake or agitate with violence.
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            Churned in his teeth, the foamy venom rose.
                                                  --Addison.
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