Churn up is a term used to describe the process of stirring or agitating a liquid or other substance. The crossword solutions for this term are AGITATE (7 letters), RILE (4 letters) and ROIL (4 letters). AGITATE means to move something with force, often in an effort to mix it with another substance. RILE means to make someone angry or upset, while ROIL means to cause something to become agitated or disturbed. All three words can be used to describe the action of churning up a substance.