Source : Webster's Revised Unabridged Dictionary (1913)

Blotch \Blotch\, n. [Cf. OE. blacche in blacchepot blacking pot,
   akin to black, as bleach is akin to bleak. See {Black}, a.,
   or cf. {Blot} a spot.]
   1. A blot or spot, as of color or of ink; especially a large
      or irregular spot. Also Fig.; as, a moral blotch.

            Spots and blotches . . . some red, others yellow.
                                                  --Harvey.

   2. (Med.) A large pustule, or a coarse eruption.

            Foul scurf and blotches him defile.   --Thomson.

Source : WordNet®

blotch
     n : an irregularly shaped spot [syn: {splodge}, {splotch}]
     v : mark with spots or blotches of different color or shades of
         color as if stained [syn: {mottle}, {streak}]