dull·er, dull·est
1. Intellectually weak or obtuse; stupid.
2. Lacking responsiveness or alertness; insensitive.
3. Dispirited; depressed.
4. Not brisk or rapid; sluggish: Business is dull.
5. Not having a sharp edge or point; blunt: a dull knife.
6. Not intensely or keenly felt: a dull ache.
7. Arousing no interest or curiosity; boring: a dull play.
8. Not bright or vivid. Used of a color: a dull brown.
9. Cloudy or overcast: a dull sky.
10. Not clear or resonant: a dull thud.
tr. & intr.v. dulled, dull·ing, dulls
To make or become dull.