I heard "I'm on cloud nine" in a song and realized it was an expression by reading it somewhere else.
I am learning English for years but I never heard of that before. I found informations about the meaning* and etymology**, but I was wondering:
- Is it a common expression ?
- Would it sound old or from elevated language ?
- How would you use it ?
* I found different explanations, always talking about an extreme happiness
** 1. Cloud classification by the US Weather Bureau in the 1950s. 2. one of the stages to enlightenment of a Bodhisattva (Buddhism)