The Collaborative International Dictionary of English v.0.48:

Stipple \Stip"ple\, v. t. [imp. & p. p. Stippled; p. pr. & vb.
   n. Stippling.] [D. stippelen to make points, to spot, dot,
   from stippel, dim. of stip a dot, spot.]
   1. To engrave by means of dots, in distinction from engraving
      in lines.
      [1913 Webster]

            The interlaying of small pieces can not altogether
            avoid a broken, stippled, spotty effect. --Milman.
      [1913 Webster]

   2. To paint, as in water colors, by small, short touches
      which together produce an even or softly graded surface.
      [1913 Webster] Stipple

The Collaborative International Dictionary of English v.0.48:

Stipple \Stip"ple\, Stippling \Stip"pling\, n. (Engraving)
   A mode of execution which produces the effect by dots or
   small points instead of lines.
   [1913 Webster]

   2. (Paint.) A mode of execution in which a flat or even tint
      is produced by many small touches.
      [1913 Webster]

WordNet (r) 3.0 (2006):

stipple
    v 1: engrave by means of dots and flicks
    2: make by small short touches that together produce an even or
       softly graded shadow, as in paint or ink
    3: apply (paint) in small dots or strokes
    4: produce a mottled effect; "The sunlight stippled the trees"
       [syn: stipple, speckle]