Short for "cumulative audience", it's the total
number of listeners a
radio station has over the course of an
average week. Total amount of time spent listening does not matter...if you listen to station A for fifteen minutes one day and station B three hours every day, you're still cumed to both stations.
If you regularly listen to
three radio stations over the course of a week, then you cume
three stations, and thos three stations would consider you part of their cume.