v.1. To represent degrees of shade or shadow in some drawing or picture, so as to give the illusion of depth: The artist shaded in the contours of the model's face in the portrait.
2. To darken some bounded area that is drawn or printed on a surface: The teacher shaded in the area where the circles overlapped with yellow chalk. I'm going to shade in the left side of this drawing with crosshatches to make it darker.