English idiom · informal · spoken & written · BrE & AmE
once in a blue moon: meaning and examples
once in a blue moon means very rarely.
muy de vez en cuando; en contadas ocasiones
No describe una frecuencia regular. Se usa para algo que ocurre muy pocas veces.
بهندرت و هر از گاهی
برای یک فاصله زمانی منظم نیست؛ درباره چیزی است که بهندرت رخ میدهد.
äußerst selten; alle Jubeljahre
Die Wendung bezeichnet keinen regelmäßigen Abstand, sondern etwas, das nur sehr selten vorkommt.
très rarement; une fois tous les trente-six du mois
Elle ne décrit pas une fréquence régulière, mais quelque chose qui arrive très rarement.
Memory hook: A blue moon feels unusual and special, just like an event that almost never happens.
How to use “once in a blue moon”
- We eat at expensive restaurants once in a blue moon.
- He only posts on social media once in a blue moon.
- Once in a blue moon, I stay in bed all morning.
Common mistake: Use it as an adverbial phrase. It answers “How often?”, not “When exactly?”.
Learn it in context
This expression belongs to Lesson 2, where you can compare it with other idioms about time and practise it interactively.
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