Sagan

Etymology
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.

Noun

 * 1)  A unit of measurement equal to at least four billion.

Anagrams

 * Angas
 * nagas, nāgas