once in a blue moon

Pronunciation

• IPA ^(key): /wʌns ɪn ə bluː muːn/

• Audio (AU)

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Expression

Expression once in a blue moon

1. (idiom) Something that happens once in a blue moon, is something that rarely happens.

   Once in a blue moon, the teacher won't give us homework.

2. (old, no longer used) Something that never happens.

Related words

• blue moon