dull in WordNet English dictionary

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

1. so lacking in interest as to cause mental weariness
   "a boring evening with uninteresting people"; "the deadening effect of some routine tasks"; "a dull play"; "his competent but dull performance"; "a ho-hum speaker who couldn't capture their attention"; "what an irksome task the writing of long letters is"- Edmund Burke; "tedious days on the train"; "the tiresome chirping of a cricket"- Mark Twain; "other people's dreams are dreadfully wearisome"
   boring  deadening  dull  ho-hum  irksome  slow  tedious  tiresome  wearisome 
   
2. slow to learn or understand; lacking intellectual acuity
   "so dense he never understands anything I say to him"; "never met anyone quite so dim"; "although dull at classical learning, at mathematics he was uncommonly quick"- Thackeray; "dumb officials make some really dumb decisions"; "he was either normally stupid or being deliberately obtuse"; "worked with the slow students"
   dense  dim  dull  dumb  obtuse  slow 
   
3. not having a sharp edge or point
   "the knife was too dull to be of any use"
   dull 
   
4. emitting or reflecting very little light
   "a dull glow"; "dull silver badly in need of a polish"; "a dull sky"
   dull 
   
5. lacking in liveliness or animation
   "he was so dull at parties"; "a dull political campaign"; "a large dull impassive man"; "dull days with nothing to do"; "how dull and dreary the world is"; "fell back into one of her dull moods"
   dull 
   
6. not keenly felt
   "a dull throbbing"; "dull pain"
   dull 
   
7. darkened with overcast
   "a dark day"; "a dull sky"; "the sky was leaden and thick"
   dull  leaden 
   
8. (of business) not active or brisk
   "business is dull (or slow)"; "a sluggish market"
   dull  slow  sluggish 
   
9. blunted in responsiveness or sensibility
   "a dull gaze"; "so exhausted she was dull to what went on about her"- Willa Cather
   dull 
   
10. being or made softer or less loud or clear
    "the dull boom of distant breaking waves"; "muffled drums"; "the muffled noises of the street"; "muted trumpets"
    dull  muffled  muted  softened 
    
11. not clear and resonant; sounding as if striking with or against something relatively soft
    "the dull thud"; "thudding bullets"
    dull  thudding 
    
12. (of color) very low in saturation; highly diluted
    "dull greens and blues"
    dull