Source : Webster's Revised Unabridged Dictionary (1913)

Midday \Mid"day`\, n. [AS. midd[ae]g. See {Mid}, a., and {Day}.]
   The middle part of the day; noon.

Midday \Mid"day`\, a.
   Of or pertaining to noon; meridional; as, the midday sun.

Source : WordNet®

midday
     n : the middle of the day [syn: {noon}, {twelve noon}, {high
         noon}, {noonday}, {noontide}]