The American Heritage® Dictionary of the English Language, 4th Edition
verb-intransitive. To transmit, as by cable, programs confined to the interests of a specific group of viewers, subscribers, or listeners, such as physicians, businesspeople, or teenagers.
v. To transmit a programme to selected individuals or groups, especially via cable
n. A programme transmitted in this manner
Word Usage
"There's a problem with comparing a radio "broadcast" to an internet "narrowcast" - 90% of what you hear on the radio is probably not stuff you'd buy so the promo value to the artist of a play on Spotify is much higher than on the radio on a per listener basis so Lady Gaga gets a lot of CD/Download sales from her Spotify listens relative to radio play."