Pronunciation: (rā'dē-ō-thon"), [key]
an on-the-air radio campaign, often lasting 24 hours or more, designed to raise money for a radio station, charity, the arts, etc., as from listeners phoning in and pledging specific donations, sometimes in exchange for gifts or premiums. Cf. telethon.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.