dull

American Heritage® Dictionary of the English Language, Fourth Edition

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

Century Dictionary and Cyclopedia

1. Stupid; foolish; doltish; blockish; slow of understanding: as, a lad of dull intellect.
2. Heavy; sluggish; drowsy; inanimate; slow in thought, expression, or action: as, a surfeit leaves one dull; a dull thinker; a dull sermon; a dull stream; trade is dull.
3. Wanting sensibility or keenness; not quick in perception: as, dull of hearing; dull of seeing.
4. Sad; melancholy; depressed; dismal.
5. Not pleasing or enlivening; not exhilarating; causing dullness or ennui; depressing; cheerless: as, dull weather; a dull prospect.
6. Gross; inanimate; insensible.
7. Not bright or clear; not vivid; dim; obscure: as, a dull fire or light; a dull red color; the mirror gives a dull reflection.
8. Not sharp or acute; obtuse; blunt: as, a dull sword; a dull needle.
9. Not keenly felt; not intense: as, a dull pain. Synonyms Silly, etc. See simple.
10. To make dull, stupid, heavy, insensible, etc.; lessen the vigor, activity, or sensitiveness of; render inanimate; damp: as, to dull the wits; to dull the senses.
11. To render dim; sully; tarnish or cloud: as, the breath dulls a mirror.
12. To make less sharp or acute; render blunt or obtuse: as, to dull a knife or a needle.
13. To make less keenly felt; moderate the intensity of: as, to dull pain.
14. To become dull or blunt; become stupid.
15. To become calm; moderate: as, the wind dulled, or dulled down, about twelve o'clock.
16. To become deadened in color; lose brightness.
17. n. A noose of string or wire used to snare fish; usually, a noose of bright copper wire attached by a short string to a stout pole.
18. To fish with a dull: as, to dull for trout.

Wiktionary

1. adj. Lacking the ability to cut easily; not sharp.
2. adj. Boring; not exciting or interesting.
3. adj. Not shiny; having a matte finish or no particular luster.
4. adj. Not bright or intelligent; stupid; slow of understanding.
5. v. transitive To render dull; to remove or blunt an edge or something that was sharp.
6. v. transitive To soften, moderate or blunt.
7. v. intransitive To lose a sharp edge; to become dull.

GNU Webster's 1913

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

WordNet 3.0

1. adj. being or made softer or less loud or clear
2. adj. slow to learn or understand; lacking intellectual acuity
3. v. become dull or lusterless in appearance; lose shine or brightness
4. v. become less interesting or attractive
5. adj. not clear and resonant; sounding as if striking with or against something relatively soft
6. v. make dull or blunt
7. adj. (of color) very low in saturation; highly diluted
8. adj. so lacking in interest as to cause mental weariness
9. adj. not keenly felt
10. v. make dull in appearance
11. adj. (of business) not active or brisk
12. adj. darkened with overcast
13. v. deaden (a sound or noise), especially by wrapping
14. adj. blunted in responsiveness or sensibility
15. adj. emitting or reflecting very little light
16. adj. lacking in liveliness or animation
17. adj. not having a sharp edge or point
18. v. make numb or insensitive
19. v. make less lively or vigorous