Once in a blue moon

26th December 2024

Once in a blue moon

We use this expression to say that something only happens extremely rarely or not at all often.
Usage
Written: 
Yes
Spoken: 
Yes
Formal: 
No
Informal: 
Yes
Example 1
How often do you go to the cinema?
I used to go all the time when I was younger, but now it's once in a blue moon.
Example 2
That restaurant is amazing. I love everything on the menu.
Yes, it's only once in a blue moon that you find one that good.