1
a
often capitalized
: the earth's natural satellite (see satellite sense 1a) 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 1
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
H. R. Haggard4
: 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
mooned; mooning; moons
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.
: to spend time in idle reverie : behave abstractedly
fans mooning over movie stars
Synonyms
Examples of moon in a Sentence
Noun
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
Verb
One of the boys mooned the crowd.
One of the boys mooned at the crowd.
Recent Examples on the Web
Mary Whitfill Roeloffs, Forbes, 14 Dec. 2024
Together, Juno’s flybys have enabled an unprecedented look at the smoldering moon, including taking observations of its poles for the first time.
—Ashley Strickland, CNN, 13 Dec. 2024
Gili Malinsky, CNBC, 11 July 2024
Everyone processes grief differently — Kate Beckinsale, in particular, recently channeled her mourning emotions into a mooning escapade following the death of her beloved cat, Clive.
—EW.com, 2 July 2024
See all Example Sentences for moon 
Examples are automatically compiled from online sources to
show current usage.
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Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
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Noun
Key Facts The moon will reach peak illumination at around 4 a.m. EST on Sunday, and will rise and set at its northernmost points on the horizon of any moon in decades.
—Mary Whitfill Roeloffs, Forbes, 14 Dec. 2024
Together, Juno’s flybys have enabled an unprecedented look at the smoldering moon, including taking observations of its poles for the first time.
—Ashley Strickland, CNN, 13 Dec. 2024
Verb
Which is to say this candidate was mooning Levine the entire conversation.
—Gili Malinsky, CNBC, 11 July 2024
Everyone processes grief differently — Kate Beckinsale, in particular, recently channeled her mourning emotions into a mooning escapade following the death of her beloved cat, Clive.
—EW.com, 2 July 2024
See all Example Sentences for moon
Dictionary Entries Near moon
Cite this Entry
“Moon.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/moon. Accessed 24 Dec. 2024.
Copy CitationKids Definition
moon
1 of 2 noun1
a
: the earth's natural satellite that shines by reflecting light from the sun and revolves about the earth in about 29½ days
2
: an unspecified and usually long period of time
took many moons to complete
moonless
adjective
-ləs
moon
2 of 2 verb
: to spend time daydreaming
Medical Definition
moon
nounLove words? Need even more definitions?
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