olemus
(a) klientuuri vähenemine või vahetumine
(b) tööjõu vahetumine
Merriam-Webster:
2: a regular, quantifiable process or rate of change that occurs in a business over a period of time as existing customers are lost and new customers are added
also : a similar process or rate of change involving loss and addition of employees, companies, etc

ülevaateid
https://en.wikipedia.org/wiki/Churn_rate