Source : Webster's Revised Unabridged Dictionary (1913)

Ramadan \Ram`a*dan"\, n. [Ar. ramad[=a]n, or ramaz[=a]n,
   properly, the hot month.] [Written also {Ramadhan},
   {Ramadzan}, and {Rhamadan}.]
   1. The ninth Mohammedan month.

   2. The great annual fast of the Mohammedans, kept during
      daylight through the ninth month.

Source : WordNet®

Ramadan
     n 1: the ninth month of the Islamic calendar; the month of
          fasting; the holiest period for the Islamic faith
     2: (Islam) a fast (held from sunrise to sunset) that is carried
        out during the Islamic month of Ramadan