sharpen become sharp or sharper; "The debate sharpened"
modify,
alter,
change make less severe or harsh or extreme; "please modify this letter to make it more polite"; "he modified his views on same-gender marriage"
dull -
become dull or lusterless in appearance; lose shine or brightness; "the varnished table top dulled with time"
change undergo a change; become different in essence; losing one's or its original nature; "She changed completely as she grew older"; "The weather changed last night"
dull -
make dull in appearance; "Age had dulled the surface"
modify,
alter,
change make less severe or harsh or extreme; "please modify this letter to make it more polite"; "he modified his views on same-gender marriage"
Dull -
deaden (a sound or noise), especially by wrapping
change undergo a change; become different in essence; losing one's or its original nature; "She changed completely as she grew older"; "The weather changed last night"
Dull -
make numb or insensitive; "The shock numbed her senses"
dull -
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"
lively filled with events or activity; "a lively period in history"
dullness without sharpness or clearness of edge or point; "the dullness of the pencil made his writing illegible"
desiccate,
arid,
desiccated lacking vitality or spirit; lifeless; "a technically perfect but arid performance of the sonata"; "a desiccate romance"; "a prissy and emotionless creature...settles into a mold of desiccated snobbery"-C.J.Rolo
bovine dull and slow-moving and stolid; like an ox; "showed a bovine apathy"
dreary,
drab lacking brightness or color; dull; "drab faded curtains"; "sober Puritan grey"; "children in somber brown clothes"
leaden,
heavy (of movement) slow and laborious; "leaden steps"
humdrum,
monotonous tediously repetitious or lacking in variety; "a humdrum existence; all work and no play"; "nothing is so monotonous as the sea"
dull -
emitting or reflecting very little light; "a dull glow"; "dull silver badly in need of a polish"; "a dull sky"
bright full or promise; "had a bright future in publishing"; "the scandal threatened an abrupt end to a promising political career"; "a hopeful new singer on Broadway"
unpolished not carefully reworked or perfected or made smooth by polishing; "dull unpolished shoes"
cloudy (of liquids) clouded as with sediment; "a cloudy liquid"; "muddy coffee"; "murky waters"
dull -
blunted in responsiveness or sensibility; "a dull gaze"; "so exhausted she was dull to what went on about her"- Willa Cather
insensitive not responsive to physical stimuli; "insensitive to radiation"
dull -
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 -
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"
stupid lacking or marked by lack of intellectual acuity
Dull -
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"