moon
noun
\ 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)
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