Source : Webster's Revised Unabridged Dictionary (1913)

Moon \Moon\, n. [OE. mone, AS. m[=o]na; akin to D. maan, OS. &
   OHG. m[=a]no, G. mond, Icel. m[=a]ni, Dan. maane, Sw.
   m[*a]ne, Goth. m[=e]na, Lith. men?, L. mensis month, Gr. ?
   moon, ? month, Skr. m[=a]s moon, month; prob. from a root
   meaning to measure (cf. Skr. m[=a] to measure), from its
   serving to measure the time. [root]271. Cf. {Mete} to
   measure, {Menses}, {Monday}, {Month}.]
   1. The celestial orb which revolves round the earth; the
      satellite of the earth; a secondary planet, whose light,
      borrowed from the sun, is reflected to the earth, and
      serves to dispel the darkness of night. The diameter of
      the moon is 2,160 miles, its mean distance from the earth
      is 240,000 miles, and its mass is one eightieth that of
      the earth. See {Lunar month}, under {Month}.

            The crescent moon, the diadem of night. --Cowper.

   2. A secondary planet, or satellite, revolving about any
      member of the solar system; as, the moons of Jupiter or
      Saturn.

   3. The time occupied by the moon in making one revolution in
      her orbit; a month. --Shak.

   4. (Fort.) A crescentlike outwork. See {Half-moon}.

   {Moon blindness}.
      (a) (Far.) A kind of ophthalmia liable to recur at
          intervals of three or four weeks.
      (b) (Med.) Hemeralopia.

   {Moon dial}, a dial used to indicate time by moonlight.

   {Moon face}, a round face like a full moon.

   {Moon madness}, lunacy. [Poetic]

   {Moon month}, a lunar month.

   {Moon trefoil} (Bot.), a shrubby species of medic ({Medicago
      arborea}). See {Medic}.

   {Moon year}, a lunar year, consisting of lunar months, being
      sometimes twelve and sometimes thirteen.

Moon \Moon\, v. t. [imp. & p. p. {Mooned}; p. pr. & vb. n.
   {Mooning}.]
   To expose to the rays of the moon.

         If they have it to be exceeding white indeed, they
         seethe it yet once more, after it hath been thus sunned
         and mooned.                              --Holland.

Moon \Moon\, v. i.
   To act if moonstruck; to wander or gaze about in an
   abstracted manner.

         Elsley was mooning down the river by himself. --C.
                                                  Kingsley.

Source : WordNet®

moon
     v 1: have dreamlike musings or fantasies while awake; "She looked
          out the window, daydreaming" [syn: {daydream}]
     2: be idle in a listless or dreamy way [syn: {moon around}, {moon
        on}]
     3: expose one's buttocks to; "moon the audience"

moon
     n 1: the natural satellite of the Earth; "the average distance to
          the moon is 384,400 kilometers"; "men first stepped on
          the moon in 1969"
     2: any object resembling a moon; "he made a moon lamp that he
        used as a night light"; "the clock had a moon that showed
        various phases"
     3: the period between successive new moons (29.531 days) [syn:
        {lunar month}, {lunation}, {synodic month}]
     4: the light of the moon; "moonlight is the smuggler's enemy";
        "the moon was bright enough to read by" [syn: {moonlight},
         {moonshine}]
     5: United States religious leader (born in Korea) who founded
        the Unification Church in 1954; was found guilty of
        conspiracy to evade taxes (born in 1920) [syn: {Sun Myung
        Moon}]
     6: any natural satellite of a planet; "Jupiter has sixteen
        moons"