1. An unethical practice employed by some brokers to increase their commissions by excessively trading in a client's account. This practice violates the NASD Fair Practice Rules. It is also referred to as "churn and burn", "twisting" and "overtrading". 2. A period of heavy trading with few sustained price trends and little movement in stock market indexes. Taobiz explains Churning Another negative result for the client is being stuck with higher tax bills.