To churn means to shake or stir something vigorously and continuously. The word comes from the old practice of making butter: you pour cream into a special container called a butter churn and agitate it for a long time until the fat separates out and becomes butter. This process requires patience and steady, repetitive motion.

Today, people use churn to describe any vigorous, ongoing stirring or mixing. A washing machine churns clothes around in soapy water. Storm waves churn up sand from the ocean floor, turning the water cloudy and rough. Your stomach might feel like it's churning when you're nervous before a big presentation.

As a noun, churn can mean the container used for making butter, or the act of churning itself.

In business, churn describes customers who stop using a service. If a streaming company has high churn, many subscribers cancel each month. Companies work hard to reduce churn because keeping existing customers is usually easier than finding new ones.

The word also means to produce something steadily and in large quantities, often without much care for quality. A factory might churn out cheap toys, or a student rushing through homework might churn out messy answers just to finish. This usage suggests speed and quantity over thoughtfulness: the cream keeps getting stirred, but you're not paying attention to what you're making.