Definitions for saganˈseɪ gən
Random House Webster's College Dictionary
Carl (Edward),1934–96, U.S. astronomer and writer.
A unit of measurement equal to at least four billion.
Origin: The unit is derived from the phrase billions and billions (of stars), frequently attributed to the American astronomer Carl Sagan. The lower bound of a number must be two billion plus two billion, or four billion. Johnny Carson popularized the phrase through his occasional impersonation of Sagan throughout his career.
The New Hacker's Dictionary
[from Carl Sagan's TV series Cosmos; think “billions and billions”] A large quantity of anything. “There's a sagan different ways to tweak EMACS.” “The U.S. Government spends sagans on bombs and welfare — hard to say which is more destructive.”