a radio programme that is stored in a digital(= using signals in the form of numbers) form that you can download from the Internet and play on a computer or on an MP3 player
podcasting noun
/ˈpɒd.kɑːst.ɪŋ//ˈpɑːd.kæst-/n[U]
the process of making digital recordings of radio programmes which people can download from the Internet