once in a blue moon
very rarely
In Spanish
very rarely
Examples
- We only go out for dinner once in a blue moon these days.
- He only calls me once in a blue moon, usually when he needs something.
- I clean out the garage once in a blue moon, so it's always messy.
When it's used
This idiom is used in informal contexts and is common in everyday speech. It can appear in both spoken and written English, but it is more frequently used in conversation. It indicates that something happens very infrequently.
The common mistake
Spanish speakers might mistakenly say 'once in a blue moon' when they mean 'every once in a while'. This doesn't work because in English, this idiom has a specific meaning and can't be used for any infrequent event.
Related idioms
FROM WHAT YOU READ TO WHAT YOU SAY
Recognising it isn't the same as using it
Reading an idiom and understanding it is step one. Dropping it into a conversation, at the right moment, without stopping to think, is another — and that only comes from speaking.
Practise speaking→