\ˈmün \

Definition of moon 

(Entry 1 of 2)

1a often capitalized : the earth's natural satellite (see satellite sense 2a) that shines by the sun's reflected light, revolves about the earth from west to east in about 29¹/₂ days with reference to the sun or about 27¹/₃ days with reference to the stars, and has a diameter of 2160 miles (3475 kilometers), a mean distance from the earth of about 238,900 miles (384,400 kilometers), and a mass about one eightieth that of the earth usually used with the

b : one complete moon cycle consisting of four phases (see phase entry 1 sense 1)

c : satellite sense 2 specifically : a natural satellite of a planet the moons of Jupiter

2 : an indefinite usually extended period of time a labor of many moons

3 : moonlight keep out of the moon or it may turn your head— H. R. Haggard

4 : something that resembles a moon: such as

a : a highly translucent (see translucent sense 1) spot on old porcelain

b : lunule

c slang : naked buttocks

5 : something impossible or inaccessible reach for the moon

over the moon

: very pleased : in high spirits


mooned; mooning; moons

Definition of moon (Entry 2 of 2)

transitive verb

1 : to spend in idle reverie : dream used with away mooned the afternoon away

2 slang : to expose one's naked buttocks to One of the boys mooned the crowd.

intransitive verb

: to spend time in idle reverie : behave abstractedly fans mooning over movie stars

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Other Words from moon


moonlike \ -​ˌlīk \ adjective

Synonyms for moon

Synonyms: Noun

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

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Examples of moon in a Sentence


The telescope makes the craters on the surface of the moon incredibly clear. the orbit of the Moon around the Earth Europa and Io are both moons of Jupiter. a planet orbited by one moon


One of the boys mooned the crowd. One of the boys mooned at the crowd.
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Recent Examples on the Web: Noun

It was named after NASA's second administrator, who spearheaded the Apollo moon landings. Marcia Dunn,, "More delay, cost for NASA's James Webb Space Telescope," 28 June 2018 Be aware, there are many astronauts in the book and movie and there will be more coming our way with next year’s 50th anniversary of the 1969 moon landing. Rick Kogan,, "'Rocket Men' is a Chicago writer's book about Apollo 8 — and a timely work about astronauts," 18 June 2018 The debut of Summit is a step towardswhat might be called that competition’s moon landing – an exascale computer, capable of a billion billion calculations per second. David Z. Morris, Fortune, "The U.S. Just Reclaimed the World's Fastest Supercomputer Mantle From China," 9 June 2018 One will be an homage to space-race documentaries, and follow the process of how American heroes pulled off the Apollo 11 moon landing. Kristi Turnquist,, "Fred Armisen and Bill Hader's 'Documentary Now!' is looking for Portland extras," 5 June 2018 His first voyage, in 1969, was as the lunar module pilot on Apollo 12, which made NASA’s second moon landing. Jamie Ducharme, Time, "Famed Astronaut Alan Bean Dies at 86," 26 May 2018 The accompanying video sends the boys, who were all between 11 and 16 at the time, to the 1969 moon landing to the sunny surf and back. Morgan Enos, Billboard, "John Mayer's 'New Light' & 8 More Music Videos That Risked Using Green Screen," 24 May 2018 The site has been a meeting place for posters who question NASA’s general veracity and those who dabble in conspiracy theories — like questioning the legitimacy of the moon landing. NBC News, "Racist trolls sabotaged a NASA competition to stop black teen girls from winning," 3 May 2018 In 1965, four years before the moon landing, a great American went into space. Sophie Gilbert, The Atlantic, "Can Barbie Really Have It All?," 1 May 2018

Recent Examples on the Web: Verb

The whole reason for mooning a group text in the first place. Madeline Buxton,, "Dear Apple, You Forgot Some Very Important "Do Not Disturb" Settings," 6 June 2018 She and Tom Arnold had mooned the crowd at a World Series game to show off their matching tattoos. Kate Stanhope,, "Rocky road: Roseanne Barr's rollercoaster Hollywood ride," 10 Apr. 2018 These days any rocketeer wishing to get staggeringly pie-eyed and maybe moon the Moon will have to hitch a ride with another space agency altogether. David Arky, Smithsonian, "How Do You Make Beer in Space?," 20 Mar. 2018 Who can forget Ilie Nastase pulling down his pants and mooning the chair umpire Charles Hare in Palm Springs in 1976? Cindy Shmerler, New York Times, "Tennis Moves Toward Taking the Human Element Out of Line Calls," 1 Mar. 2018 The old Birmingham guard repaid the favor by using the worlds' largest cast iron statue to perpetually moon the little town that preferred seeking its own stars. Birmingham Magazine,, "A History of Homewood," 19 Feb. 2018 Until Sunday the biggest threat was guests occasionally mooning or flashing partygoers, says DJ cb shaw, who was a resident DJ at Rehab for six years. Alexei Barrionuevo, Billboard, "Dance Music Industry Says Pool Parties Could Be Vulnerable Following Las Vegas Shooting," 5 Oct. 2017 Having washed up on the Illyrian shore as a stranger in a strange land, Viola has been dispatched to sing the love of her new employer: the lovesick Duke Orsino (Demetrios E. Troy), mooning over Countess Olivia (Deborah Staples). Mike Fischer, Milwaukee Journal Sentinel, "Elyse Edelman brings new dimension to Door Shakespeare's 'Twelfth Night'," 17 July 2017 Among the actions that remain banned are those depicting a weapon or aimed at embarrassing opponents like Randy Moss pretending to moon the fans at Lambeau Field or Terrell Owens... Michael Salfino, WSJ, "The NFL’s New Touchdown Rules Could Endanger the Lambeau Leap," 24 May 2017

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

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First Known Use of moon


before the 12th century, in the meaning defined at sense 1a


1836, in the meaning defined at transitive sense 1

History and Etymology for moon


Middle English mone, from Old English mōna; akin to Old High German māno moon, Latin mensis month, Greek mēn month, mēnē moon


see moon entry 1

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Learn More about moon

Dictionary Entries near moon





moon's man

moon after


Statistics for moon

Last Updated

5 Nov 2018

Look-up Popularity

Time Traveler for moon

The first known use of moon was before the 12th century

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More Definitions for moon



English Language Learners Definition of moon

 (Entry 1 of 2)

the moon : the large round object that circles the Earth and that shines at night by reflecting light from the sun

: a large round object like the moon that circles around a planet other than the Earth



English Language Learners Definition of moon (Entry 2 of 2)

: to bend over and show your bare buttocks to someone as a rude joke or insult


\ˈmün \

Kids Definition of moon

 (Entry 1 of 2)

1 : the natural heavenly body that shines by reflecting light from the sun and revolves about the earth in about 29¹/₂ days


mooned; mooning

Kids Definition of moon (Entry 2 of 2)


\ˈmün \

Medical Definition of moon 

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More from Merriam-Webster on moon

Thesaurus: All synonyms and antonyms for moon

Spanish Central: Translation of moon

Nglish: Translation of moon for Spanish Speakers

Britannica English: Translation of moon for Arabic Speakers

Comments on moon

What made you want to look up moon? Please tell us where you read or heard it (including the quote, if possible).


full of whispering sounds

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