Definition of on cloud nine
- He's been on cloud nine ever since she agreed to marry him.
: a visible mass of particles of condensed vapor (such as water or ice) suspended in the atmosphere of a planet (such as the earth) or moon
: something resembling or suggesting a cloud: such as
: a light filmy, puffy, or billowy mass seeming to float in the air
: to grow cloudy
: to become troubled, apprehensive, or distressed in appearance
: to become blurry, dubious, or ominous
What made you want to look up on cloud nine? Please tell us where you read or heard it (including the quote, if possible).