Definition of dull :
1. Furnishing little delight, spirit, or variety; uninteresting; tedious; cheerless; gloomy; melancholy; depressing; as, a dull story or sermon; a dull occupation or period; hence, cloudy; overcast; as, a dull day.
2. Heavy; gross; cloggy; insensible; spiritless; lifeless; inert.
3. Insensible; unfeeling.
4. Not bright or clear to the eye; wanting in liveliness of color or luster; not vivid; obscure; dim; as, a dull fire or lamp; a dull red or yellow; a dull mirror.
5. Not keen in edge or point; lacking sharpness; blunt.
6. Slow in action; sluggish; unready; awkward.
7. Slow of understanding; wanting readiness of apprehension; stupid; doltish; blockish.
8. To become dull or stupid.
9. To deprive of liveliness or activity; to render heavy; to make inert; to depress; to weary; to sadden.
10. To deprive of sharpness of edge or point.
11. To make dull, stupid, or sluggish; to stupefy, as the senses, the feelings, the perceptions, and the like.
12. To render dim or obscure; to sully; to tarnish.
dawdling, delaying, black, grave, rusty, accustomed, mind-numbing, dimmed, wearying, monochromatic, subdued, soggy, dismal, dun, airheaded, numbing, wordy, chuckleheaded, clouded, daunt, chapped, cirrus, moisten, fascinating, attitude, underfunded, deadening, uninspiring, dispirited, burning, sulky, inactive, non compos mentis, frighten off, skew, wearing, excite, brainless, pack a punch, platitudinous, round, chronic, murky, uninspired, verbose, happy, turned, simple, awareness, sordid, dampen, stuporous, unsaturated, slack, dirty, conventional, hushed, wistful, quieten, matted, unreverberant, tiring, matte, hollow, silent, muddy, lively, increase, wooden, square, dash, jade, tone down, irksome, moderate, bright, desiccated, banal, color, broken, exciting, feelings, acute, unhappy, simple-minded, routine, strangle, trite, agonising, cirrocumulus, gradual, thudding, regular, melancholic, dim-witted, blunted, stereotypical, cloudy, archaic, tame, tardy, unintelligent, cumulus, fatuous, low, nonresonant, silly, sad, lingering, opaque, well-known, barbed, soft, dejected, anesthetic, achy, prosy, backward, brain-dead, decide, blind, frighten away, light, pedestrian, vapid, usual, give, procrastinating, empty-headed, common, barren, wan, feeble-minded, unimaginative, scare off, down, stereotyped, windy, purblind, wash, bank, birdbrained, ho-hum, trivial, smother, weariful, stagnant, dysphoric, grimy, plangent, stimulating, keen, spiritless, sterile, colorful, untapped, dorky, aseptic, abused, fatiguing, dilatory, pinheaded, thick, ability, bass, resonant, washy, hoary, slow-witted, left-handed, unsmart, sharp, vacuous, sober, even, lowering, bland, repetitive, wispy, heavy-hearted, well-worn, mat, addled, pitchy, overclouded, Grey, desiccate, low-pitched, colors, gormless, moronic, long-winded, muted, antediluvian, grip, drear, retarded, blockheaded, pall, drudging, matt, softened, bubbleheaded, unhealthy, thickheaded, speechless, downhearted, imbecilic, stodgy, gentle, beclouded, scatterbrained, softheaded, witty, uneconomical, influence, block out, cirrostratus, ordinary, prolix, inert, cut out, washed-out, lustreless, razor-sharp, mindless, bleak, loss-making, tristful, cloy, stale, out-of-date, half-witted, cloud, boneheaded, uneventful, sooty, weak-minded, stifle, not-for-profit, dusty, stuffy, nonprofit, inky, unvarying, dusky, shallow, edgeless, unresponsive, old, see, idiotic, pastel, insensate, bad, lacklustre, weighted, oafish, ancient, plain, angry, blue, jading, stock, bloodless, crippling, hazy, two-edged, poky, break, desolate, downcast, obscure, unprofitable, heavy, familiar, quick, uncomprehending, deliberate, quiescent, placid, witless, vague, dumb, impenetrable, lunkheaded, damp, matter-of-fact, thumping, hazed, unexciting, melancholy, worn-out, lead to, double-edged, column, billow, lumpy, weak, dimwitted, plodding, arid, repress, serrated, catch, off, dulled, hackneyed, stolid, razor-edged, scare, bonehead, become flat, jejune, flavorless, active, dunderheaded, ignorant, stir, drown, repetitious, deadly, earthbound, agonizing, shadowy, lamebrain, uneconomic, dark, depressed, scare away, knuckleheaded, used, die, cumulonimbus, deep
grayness (part of speech: noun)
lethargic (part of speech: adjective)
bore (part of speech: verb)
dull (part of speech: adjective)
blunt (part of speech: verb)
gray (part of speech: adjective)
gray, ashen, gun metal, pearly, pearl-gray, neutral-tint, dingy, mousy, salt-and-pepper, dapple-gray, battleship-gray, grizzled, smoky, gloomy, somber, lead-gray, silvery, taupe, drab, dreary, iron-gray, mole-gray
disable (part of speech: verb)
hamper, invalidate, deaden, tamper, disarm, hobble, benumb, neutralize, cripple, weaken, abrogate, hinder, botch, cramp, undermine, scotch, hamstring, vitiate, incapacitate, prostrate, handicap, sap, impair, anesthetize, enfeeble, disable, screw up, stun, paralyze, lame, stupefy
boring (part of speech: adjective)
numb (part of speech: verb)
colorless (part of speech: adjective)
quiet (part of speech: verb)
senseless (part of speech: adjective)
insentient, unperceptive, soporific, numb, trance-like, dead, aloof, oblivious, faint, anesthetized, senseless, callous, insensible, blacked out, swooning, unconscious, unfeeling, comatose, stupid, narcotic, insensitive
non-resonant (part of speech: adjective)
- Thou, born of stern necessity, Dull peace! - "Minstrelsy of the Scottish border (3rd ed) (1 of 3)", Walter Scott.
- It has been a pleasure to talk to you, for the days are very long and very dull. - "The Squire's Daughter", Silas K(itto) Hocking.
- The book has not a dull line in it. - "Admiral Farragut", A. T. Mahan.