1. [adj]  deprived of color; "colors dulled by too much sun"; "grayed with the dust of the road"
2. [adj]  made dull or blunt
3. [adj]  having lost or been caused to lose interest because of overexposure; "the mind of the audience is becoming dulled"; "the benumbed intellectual faculties can no longer respond"

DULLED is a 6 letter word that starts with D.