Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio.
Slang a condition of great joy or bliss; euphoric state
Used by arrangement with John Wiley & Sons, Inc.
noun InformalThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A state of elation or great happiness: was on cloud nine after winning the marathon.