once in a lifetime
idiomPart oflifetime
once in a lifetime — idiom
1. so rare and special that it is not expected to happen again to the same person
1.idiom
Definition
so rare and special that it is not expected to happen again to the same person
Example
Seeing the northern lights in person was a once-in-a-lifetime experience for Amihan.
Eitan knew that such a job offer came once in a lifetime, so he accepted immediately.