billionaire definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a person whose wealth comes to at least a billion dollars, pounds, francs, etc.
Origin: billion plush (million)aire
billionaire definition by American Heritage Dictionary
A person whose wealth amounts to at least a billion dollars, pounds, or the equivalent in other currency.
Origin: billion + (million)aire.