Dull

1. To deprive of sharpness of edge or point.
2. To render dim or obscure; to sully; to tarnish.
3. Not keen in edge or point; lacking sharpness; blunt.
4. Slow of understanding; wanting readiness of apprehension; stupid; doltish; blockish.
5. Furnishing little delight, spirit, or variety; uninteresting; tedious; cheerless; gloomy; melancholy; depressing; as, a dull story or sermon; a dull occupation or period; hence, cloudy; overcast; as, a dull day.
6. Slow in action; sluggish; unready; awkward.
7. To deprive of liveliness or activity; to render heavy; to make inert; to depress; to weary; to sadden.
8. To make dull, stupid, or sluggish; to stupefy, as the senses, the feelings, the perceptions, and the like.
9. Insensible; unfeeling.
10. Heavy; gross; cloggy; insensible; spiritless; lifeless; inert.
11. To become dull or stupid.
12. Not bright or clear to the eye; wanting in liveliness of color or luster; not vivid; obscure; dim; as, a dull fire or lamp; a dull red or yellow; a dull mirror.