blue moons
Once in forever
A blue moon is the second full moon occurring within a single calendar month, a relatively rare event that happens roughly every two to three years.
The phrase once in a blue moon means very rarely or almost never.
Occasionally, atmospheric conditions such as volcanic ash or forest fire smoke can make the moon appear literally blue, though this is even rarer than the calendrical phenomenon.
- infrequencyState of occurring seldom
- rare occurrenceInfrequent happening
- lifetimesComplete spans of being
- phenomenonExtraordinary observable occurrence
- rarityUncommon occurrence
few and far between · colloquialisms · ages · anomaly · aeons · eternities · one-of-a-kind · sporadic · once in a lifetime · when pigs fly · rare as hen's teeth · irregularity · supermoon · exceptional · seldom · occasional · special occasion · extraordinary
blue moonsdime a dozen
Abundant and unremarkable
all the time · every day · habitual patterns · the usual · standard fare
blue moonspar for the course
Usual, predictable outcome
the usual · bread and butter · same old same old · business as usual · standard fare
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