once in a blue moon


once in a blue moon


  • very rarely
  • once after a long time
  • something that happens very seldom
  • on rare occasions
  • almost never
  • hardly ever

Example Sentences

  1. The earthquakes hits once in a blue moon in this part of the earth, we never felt it.
  2. I don’t know why she bought that music system – she uses it once in a blue moon.
  3. “I think my grandson doesn’t love me anymore, he comes to see me only once in a blue moon.”
  4. My Dad is working in Scotland and he visits home once in a blue moon, every couple of years.
  5. Although I trust in God, I visit that famous temple only once in a blue moon.


The concept behind the origination of this idiom is second but rare appearance of the full moon in same month. Blue moon is the full moon that appears second time in same calendar month and this phenomenon happens only once in 32 months. Apart from that, sometime the full moon appears to be different in colour specially blue and orange and bigger in size.

The earliest known recorded use of another version of the idiom is in an anti-clerical booklet printed in 1528 by William Roy and Jeremy Barlowe. In a discussion between two characters.

“O churche men are wyly foxes […] Yf they say the mone is blewe / We must beleve that it is true / Admittynge their interpretacion.”

It seems to be a reference to priests at the time making statements and expecting the average person to trust they were right, irrespective of how ridiculous it was. It is something like the original usage of the “moon is made of green cheese,” in that case referring to the fact that only fools would trust that.

In its current form, the idiom dates back to 1821 with the publication of Real Life in London by Pierce Egan.

In the book, one character says to another.

“How’s Harry and Ben? – haven’t seen you this blue moon.”

Since then, the expression has developed into a famous common saying.

Share your opinions8 Opinions

It is obviously made out of yellow cheese, if anything.

‒ Anonymous June 24, 2021

To do something “once in a blue moon” is to do it very rarely: “That company puts on a good performance only once in a blue moon.” The phrase refers to the appearance of a second full moon within a calendar month, which actually happens about every thirty-two months.

‒ Freya April 26, 2020

I visited tiger sanctuary that is established at Kanha district Madhya Pradesh, India in the month of December, so, tiger safari guide said to us tiger noticed inside resort’s periphery as once in blue moon.

‒ Kirtan February 19, 2020

My wife who was born in Maui where the the night skies shimmer with stars, adds the distinction, “Once in a Great Blue Moon.”

‒ Hoist Petard January 20, 2020

I have seen a red blood moon twice. It happened this year twice.

Thanks, helped a lot.

‒ Zita November 7, 2018

As I don’t I like to do plagiarism, I would like to give you the academic honesty for helping me a lot in making my speech gorgeous.

‒ Moksh March 29, 2018

Once I saw a red blood and blue moon 🌕

‒ Tanushka February 11, 2018

I think the definition is incorrect. The phrase “once in a blue moon” is an Indian phrase for the 4th full moon of a season, Europeans came along and started calling the 2nd full moon of a month a blue moon. The time between a true blue moon is much longer than 32 months.

‒ Dale Dealing February 2, 2018

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