In research: the percent of consumer research panelists who leave the panel during a given time period (typically a year). This may occur for a number of reasons, including a change in internet service provider (ISP), a new email address, a move or diminished interest. The reciprocal of churn is “panel tenure” or the length of time panelists remain active in a panel. In marketing and media: the percent who do not renew (e.g., a magazine subscription, music streaming service, video streaming service, etc.) in a given period of time. Source.