Idiom
once in a blue moon
Meanings
Very rarely; at long and irregular intervals.
Definition
Very rarely; almost never.
If something happens once in a blue moon, it happens very rarely and not often at all. People use it to emphasize that an event is unusual or infrequent. It is common in everyday conversation and often refers to activities, meetings, or visits.
Examples
- I eat fast food once in a blue moon.
- We see our cousins once in a blue moon because they live overseas.
- She goes out dancing once in a blue moon.
- My old laptop still works, but it freezes once in a blue moon.
- They argue once in a blue moon, but usually they get along.
Common mistake
Learners sometimes use it for frequent events, but it should only describe something that happens very rarely.
More at B2 level
- Bob's your uncle Used to say that something will be easy or will happen exactly as expected after a simple step.
- touch base To touch base means to briefly contact someone to share updates, confirm plans, or check progress.
- ballpark figure A ballpark figure is an approximate number or estimate, not an exact one.
- take the mickey To take the mickey means to mock someone or tease them in an unkind or cheeky way.
- cheap as chips Very cheap; costing very little money.
More idiom (adverbial phrase)s
- come hell or high water Used to emphasize that you will do something no matter what difficulties happen.
- in a nutshell “In a nutshell” means in a very brief and clear summary.
- by the book If you do something by the book, you follow the official rules exactly.
- out of left field Used to describe something surprising or unexpected, especially because it seems unrelated to what …
- down the line At a later time in the future, often after some delay or further development.