Once in a Blue Moon

Meaning Of Idiom ‘Once in a Blue Moon’

Once in a blue moon means not very often; very rarely; only once in a long period of time; practically never. 1Heacock, Paul. Cambridge Dictionary of American Idioms. Cambridge: Cambridge UP, 2010. ,2Ammer, Christine.  American Heritage Dictionary of Idioms. Boston: Houghton Mifflin Harcourt, 2013. ,3Kirkpatrick, Elizabeth M. The Wordsworth Dictionary of Idioms. Ware: Wordsworth, 1995.

Examples Of Use

“I only get to see my family once in a blue moon now that I live in France.”

“I used to paint all the time. Now I only do it once in a blue moon.”

“Once in a blue moon someone surprises you and does something decent.”

Once in a blue moon idiom meaning

Origin

Although the moon can appear blue and a full blue moon is not very rare, the color blue was used arbitrarily in this phrase, since the 1500s, to say that something could not occur or be true. Since the moon is never actually blue (or red, yellow, green, etc.) to say that something occurs once in a ‘blue’ moon is to say that it [almost] never occurs. 4Kirkpatrick, Elizabeth M. The Wordsworth Dictionary of Idioms. Ware: Wordsworth, 1995.

More Idioms Starting with O

More Blue Idioms

More Color Related Idioms

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Sources   [ + ]

1. Heacock, Paul. Cambridge Dictionary of American Idioms. Cambridge: Cambridge UP, 2010.
2. Ammer, Christine.  American Heritage Dictionary of Idioms. Boston: Houghton Mifflin Harcourt, 2013.
3, 4. Kirkpatrick, Elizabeth M. The Wordsworth Dictionary of Idioms. Ware: Wordsworth, 1995.