blue moon

noun

Definition of blue moon

1 : a very long period of time —usually used in the phrase once in a blue moon such people happen along only once in a blue moon — Saturday Rev.

2 : a second full moon in a calendar month

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Synonyms for blue moon

Synonyms

aeon (or eon), age, coon's age, cycle, donkey's years [chiefly British], eternity, forever, long, months, moon

Examples of blue moon in a Sentence

once in a blue moon we'll get dressed up and eat in a fancy restaurant

Recent Examples on the Web

This is also the second month in 2018 with a blue moon. — Leigh Morgan, AL.com, "Blue moon 2018: Second -- and last -- blue moon of year rises tonight," 1 Dec. 2017 The unicorn will join seven other marshmallow shapes: hearts, stars, horseshoes, clovers, blue moons, rainbows, red balloons. — Brett Molina, USA TODAY, "Lucky Charms is retiring one of its marshmallows to add a unicorn," 20 Feb. 2018 The full moon on that date happens to be the second full moon of the month, or a blue moon. — Jay Bennett, Popular Mechanics, "The Most Spectacular Eclipse of 2018 Is Tomorrow," 30 Jan. 2018 The second blue moon of the year, appearing Saturday morning, will be the last until 2020. — Ashley May, USA TODAY, "Saturday morning is the last chance to see a blue moon until 2020," 30 Mar. 2018 Coincidentally, Venus also governs Libra, so the second full moon of the month — this phenomenon is called a blue moon — emphasizes partnerships. — Aliza Kelly Faragher, Allure, "What Your Sign's March 2018 Horoscope Predictions Mean for You," 28 Feb. 2018 Barring clouds in the northwest sky, Wednesday's total eclipse of the blue moon will be visible low in the western sky. — Mike De Sisti, Milwaukee Journal Sentinel, "How to photograph, make the super-blood-blue-moon total eclipse a family event," 30 Jan. 2018 The colorful new addition—a white unicorn with purple and blue highlights—will join the current mainstays: heart, star, horseshoe clover, blue moon and red balloon marshmallows—and replace the hourglass, which was retired earlier this month. — Collier Sutter, PEOPLE.com, "Lucky Charms Debuts a New Marshmallow for the First Time in a Decade," 20 Feb. 2018 The rare blue blood moon was combination of a supermoon, blue moon and total lunar eclipse. — Ashley May, USA TODAY, "Incredible images of the rare blue blood moon," 31 Jan. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'blue moon.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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Dictionary Entries near blue moon

Blue Mountain tea

Statistics for blue moon

Last Updated

11 Mar 2019

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Time Traveler for blue moon

The first known use of blue moon was in 1821

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