1. Lacking in liveliness or animation
   "he was so dull at parties"; "a dull political campaign"; "dull days with nothing to do"; "fell back into one of her dull moods";
   - hebetudinous [rare]
    
2. So lacking in interest as to cause mental weariness
   "a dull play"; "his competent but dull performance";
   - boring, deadening, ho-hum [informal], irksome, slow, tedious, tiresome, wearisome, unamusing, deadly [informal], draggy [informal], mind-numbing
    
3. Emitting or reflecting very little light
   "a dull glow"; "dull silver badly in need of a polish"
    
4. Not having a sharp edge or point
   "the knife was too dull to be of any use"
    
5. Taking more than usual time to learn or understand; lacking intellectual acuity
   "although dull at classical learning, at mathematics he was uncommonly quick";
   - dense, dim [informal], dumb, obtuse, slow
    
6. (of business) not active or brisk
   "business is dull";
   - slow, sluggish
    
7. (of colour) very low in saturation; highly diluted
   "dull greens and blues"
    
8. Being or made softer or less loud or clear
   "the dull boom of distant breaking waves";
   - muffled, muted, softened
    
9. Not clear and resonant; sounding as if striking with or against something relatively soft
   "the dull thud";
   - thudding
    
10. Not keenly felt
    "a dull throbbing"; "dull pain"
     
11. Blunted in responsiveness or sensibility
    "a dull gaze"; "so exhausted she was dull to what went on about her"
     
12. Darkened with overcast
    "it was a dull day";
    - leaden

1. Make dull in appearance
   "Age had dulled the surface"
    
2. Become dull or lusterless in appearance; lose shine or brightness
   "the varnished table top dulled with time"
    
3. Make dull or blunt
   "Too much cutting dulls the knife's edge";
   - blunt
    
4. Become less interesting or attractive
   "The constant repetition dulled the impact of the message";
   - pall
    
5. Make less lively or vigorous
   "Middle age dulled her appetite for travel"
    
6. Deaden (a sound or noise), especially by wrapping
   "They dulled the drum sound with blankets";
   - muffle, mute, damp, dampen, tone down
    
7. Make numb or insensitive
   "The shock dulled her senses";
   - numb, benumb, blunt

Derived forms: dulling, dullest, duller, dulls, dulled

See also: arid, blunt, blunted, bovine, brightness, brightness level, cloudy, colorless [US], colourless [Brit, Cdn], daft [Brit, informal], deadened, desiccate, desiccated, drab, dreary, dulled, dullness, dumb, edgeless, flat, foolish, heavy, humdrum, imbecile, imbecilic, inactive, insensitive, lackluster [US], lacklustre [Brit, Cdn], lame, lameo [informal], leaden, light, luminance, luminosity, luminousness, lusterless [N. Amer], lustreless [Brit, Cdn], mat, matt, matte, matted, meh [informal], monotonous, monotonousness, nonresonant, samey [Brit, informal], soft, spiritless, stupid, subdued, unanimated, uninspiring, uninteresting, unpolished, unreverberant, unsaturated, unsharpened

Type of: alter, change, desensitise [Brit], desensitize, modify, soften, weaken

Antonym: bright, lively, sharp

Encyclopedia: Dull, Perthshire