churn
Key business metric: percentage of customer subscription loss.
When used in a business context. noun: Churn is used when referring to 'churn rate'. Churn rate or churn, is the percentage of people that stop using or subscribing to a service within a certain time frame. For a business to be profitable, its growth rate must exceed its churn. As well as customer churn, there is revenue churn. verb: These customers that have left have 'churned'.
Calculating churn can be simple. To find the percentage of customers that have churned, take the number of customers you have lost during a time frame, for example a month, and divide it by the number of customers you had at the beginning of that month.