1. To shake quickly and often: Athena's mother still churns cream to make fresh butter for her family as she did when she lived on a dairy farm as a young girl.
2. To vigorously move around: One day and night, while Sam and his wife were on a cruise ship, the sea was violently churning causing many of the passengers to become seasick.
3. Feeling sick from nervousness, disgust, etc.: Mark's stomach was churning as he started to get ill with influenza.

Just thinking about the final exams, that she would have to take in her university classes, made Pearl's stomach churn.

The terrible violence in the movie churned Kent's stomach.

4. To frequently buy and sell a client's securities: In order to generate more commissions, the broker encouraged his customers to churn their investments often.
5. To produce as part of a continuous process: Ingrid churns out a new novel every six months.