On cloud nine means floating with pure happiness. She was on cloud nine, still on cloud nine, left him on cloud nine.
It is reserved for the top of the scale, since somebody on cloud nine cannot be made happier. Why nine is unclear, and the earlier versions of the phrase used seven.
1phraseon cloud nineFloating with pure happiness.
“When she got the job offer, she was on cloud nine for days.”
on cloud nine is a happiness.
Also accepted in games: over the moon
From cloud nine, of uncertain origin; earlier versions of the phrase used seven.
See cloud nine.
Etymology from Wiktionary, CC BY-SA
Practised in Idioms