become dull or lusterless in appearance; lose shine or brightness
"the varnished table top dulled with time"
To render dull; to remove or blunt an edge or something that was sharp.
"The heavy rock struck the knife and dulled its blade instantly."
In plain English: To dull something means to make it less sharp, bright, or effective by hitting or rubbing against another object.
"The long lecture began to dull his interest in the subject."
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"
emitting or reflecting very little light
"a dull glow"
"dull silver badly in need of a polish"
"a dull sky"
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"
"tedious days on the train"
"the tiresome chirping of a cricket"
"other people's dreams are dreadfully wearisome"
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"
"dumb officials make some really dumb decisions"
"he was either normally stupid or being deliberately obtuse"
"worked with the slow students"
blunted in responsiveness or sensibility
"a dull gaze"
"so exhausted she was dull to what went on about her"
Lacking the ability to cut easily; not sharp.
"The dull knife struggled to slice through the tomato without squishing it."
In plain English: Dull means lacking interest, excitement, or brightness.
"The movie was very dull and I found myself falling asleep halfway through."
Usage: Use "dull" as an adjective to describe objects lacking a sharp cutting edge, such as a knife or blade. When referring specifically to removing bluntness from a tool, use it as a verb meaning to render something less sharp through friction or impact.
A surname. of Scottish and German origin.
"After visiting Dull, we drove back to our hotel feeling refreshed by the quiet Scottish countryside."
A village in Perth and Kinross council area, Scotland.
The word "dull" comes from Old English dol, which originally meant foolish or erring. Its roots trace back to a Proto-Indo-European term meaning to dim, cloud, or make obscure.