dull

Etymology

From Middle English dull, dul (also dyll, dill, dwal), from Old English dol (“dull, foolish, erring, heretical; foolish, silly; presumptuous”), from Proto-West Germanic *dol, from Proto-Germanic *dulaz, from earlier *dwulaz, a variant of *dwalaz (“stunned, mad, foolish, misled”), from Proto-Indo-European *dʰwel-, *dʰewel- (“to dim, dull, cloud, make obscure, swirl, whirl”). Cognate with Scots dull, doll (“slow to understand or hear, deaf, dull”), North Frisian dol (“rash, unthinking, giddy, flippant”), Dutch dol (“crazy, mad, insane”), Low German dul, dol (“mad, silly, stupid, fatuous”), German toll (“crazy, mad, wild, fantastic”), Danish dval (“foolish, absurd”), Icelandic dulur (“secretive, silent”), West-Flemish dul (angry, furious).

adj

1. Lacking the ability to cut easily; not sharp.
   All these knives are dull.
2. Boring; not exciting or interesting.
   He sat through the dull lecture and barely stayed awake.
   "You are very dull this morning, Sheriff," said the youngest daughter of the house, who, being the baby and pretty, had grown pettishly privileged in speech. 1895, S. R. Crockett, A Cry Across the Black Water
3. Not shiny; having a matte finish or no particular luster or brightness.
   Choose a dull finish to hide fingerprints.
   a dull fire or lamp;  a dull red or yellow;  a dull mirror
4. Not bright or intelligent; stupid; having slow understanding.
   She paused and took a defiant breath. ‘If you don't believe me, I can't help it. But I'm not a liar.’ ¶ ‘No,’ said Luke, grinning at her. ‘You're not dull enough! […] What about the kid's clothes? I don't suppose they were anything to write home about, but didn't you keep anything? A bootee or a bit of embroidery or anything at all?’ 1963, Margery Allingham, chapter 15, in The China Governess
5. Sluggish, listless.
6. Cloudy, overcast.
   It's a dull day.
7. Insensible; unfeeling.
8. Heavy; lifeless; inert.
   c. 1857', Henry Wadsworth Longfellow, Table-Talk As turning the logs will make a dull fire burn, so changes of study a dull brain.
9. (of pain etc) Not intense; felt indistinctly or only slightly.
   Pressing on the bruise produces a dull pain.
10. (of a noise or sound) Not clear, muffled.

verb

1. (transitive) To render dull; to remove or blunt an edge or something that was sharp.
   Years of misuse have dulled the tools.
2. (transitive) To soften, moderate or blunt; to make dull, stupid, or sluggish; to stupefy.
   He drinks to dull the pain.
   Use and custom have so dulled our eyes. 1850, Richard Chenevix Trench, Notes on the Miracles of Our Lord
3. (intransitive) To lose a sharp edge; to become dull.
   A razor will dull with use.
4. To render dim or obscure; to sully; to tarnish.