stippling

动词 stipple:

1. engrave by means of dots and flicks
   同义词：stipple
2. make by small short touches that together produce an even or softly graded shadow, as in paint or ink
   同义词：stipple
3. apply (paint) in small touches
   同义词：stipple
4. produce a mottled effect
   同义词：stipple, speckle