dullest

"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"

"a dull glow"
"dull silver badly in need of a polish"
"a dull sky"

"the dull boom of distant breaking waves"
"muffled drums"
"the muffled noises of the street"
"muted trumpets"

"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"
"tedious days on the train"
"the tiresome chirping of a cricket"
"other people's dreams are dreadfully wearisome"

"dull greens and blues"

"a dull throbbing"
"dull pain"

"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"
"dumb officials make some really dumb decisions"
"he was either normally stupid or being deliberately obtuse"
"worked with the slow students"

"business is dull (or slow)"
"a sluggish market"

"the knife was too dull to be of any use"

"a dull gaze"
"so exhausted she was dull to what went on about her"

"the dull thud"
"thudding bullets"

"a dark day"
"a dull sky"
"the sky was leaden and thick"

"Age had dulled the surface"

"the varnished table top dulled with time"

"The shock numbed her senses"

"Too much cutting dulls the knife's edge"

"Middle age dulled her appetite for travel"