1.  dullness(n = noun.cognition) obtuseness - the quality of being slow to understand;
is a kind of stupidity
has particulars: oscitance, oscitancy
Derived form adjective dull₇

2.  dullness(n = noun.attribute) - the quality of lacking interestingness; "the stories were of a dullness to bring a buffalo to its knees"
is a kind of uninterestingness
has particulars: boringness, dreariness, insipidity, insipidness, tediousness, tedium, tiresomeness, jejuneness, jejunity, tameness, vapidity, vapidness
Derived forms adjective dull₁, adjective dull₄

3.  dullness(n = noun.attribute) - a lack of visual brightness; "the brightness of the orange sky was reflected in the dullness of the orange sea"
is a kind of visual property
has particulars: dimness, subduedness, flatness, lusterlessness, lustrelessness, mat, matt, matte
Antonym: brightness
Derived forms adjective dull₂, adjective dull₅, adjective dull₁₂

4.  dullness(n = noun.attribute) - lack of sensibility; "there was a dullness in his heart"; "without him the dullness of her life crept into her work no matter how she tried to compartmentalize it."
is a kind of callosity, callousness, hardness, insensibility, unfeelingness
Derived forms adjective dull₆, adjective dull₁₀

5.  dullness(n = noun.attribute) bluntness - without sharpness or clearness of edge or point; "the dullness of the pencil made his writing illegible"
is a kind of configuration, conformation, contour, form, shape
has particulars: obtuseness
Antonyms: sharpness, sharpness
Derived form adjective dull₉

N  inactivity, inaction, inertness, obstinacy, lull, quiescence, rust, rustiness, idleness, remissness, sloth, indolence, indiligence, dawdling, ergophobia, otiosity, dullness, languor, segnity, segnitude, lentor, sluggishness, procrastination, torpor, torpidity, torpescence, stupor, somnolence, drowsiness, nodding, oscitation, oscitancy, pandiculation, hypnotism, lethargy, statuvolence heaviness, heavy eyelids, sleep, slumber, sound sleep, heavy sleep, balmy sleep, Morpheus, Somnus, coma, trance, ecstasis, dream, hibernation, nap, doze, snooze, siesta, wink of sleep, forty winks, snore, hypnology, dull work, pottering, relaxation, Castle of Indolence, lullaby, sedative, tranquilizer, hypnotic, sleeping pill, relaxant, anaesthetic, general anaesthetic, torpedo, idler, drone, droil, dawdle, mopus, do- little faineant, dummy, sleeping partner, afternoon farmer, truant, bummer, loafer, goldbrick, goldbicker, lounger, lazzarone, lubber, lubbard, slow coach (slow, ), opium eater, lotus eater, slug, lag, sluggard, slugabed, slumberer, dormouse, marmot, waiter on Providence, fruges consumere natus, inactive, motionless, unoccupied, unbusied, indolent, lazy, slothful, idle, lusk, remiss, slack, inert, torpid, sluggish, otiose, languid, supine, heavy, dull, leaden, lumpish, exanimate, soulless, listless, drony, dronish, lazy as Ludlam's dog, dilatory, laggard, lagging, slow, rusty, flagging, lackadaisical, maudlin, fiddle-faddle, pottering, shilly-shally, sleeping asleep, fast asleep, dead asleep, sound asleep, in a sound sleep, sound as a top, dormant, comatose, in the arms of Morpheus, in the lap of Morpheus, sleepy, sleepful, dozy, drowsy, somnolent, torpescent, lethargic, lethargical, somnifacient, statuvolent, statuvolic, heavy, heavy with sleep, napping, somnific, somniferous, soporous, soporific, soporiferous, hypnotic, balmy, dreamy, unawakened, unawakened, sedative, inactively, at leisure, the eyes begin to draw straws, bankrupt of life yet prodigal of ease, better 50 years of Europe than a cycle of Cathay, idly busy rolls their world away, the mystery of folded sleep, the timely dew of sleep, thou driftest gently down the tides of sleep, tired Nature's sweet restorer, balmy sleep.

N  insensibility, insensibleness, moral insensibility, inertness, inertia, vis inertiae, impassibility, impassibleness, inappetency, apathy, phlegm, dullness, hebetude, supineness, lukewarmness, cold fit, cold blood, cold heart, coldness, coolness, frigidity, sang froid, stoicism, imperturbation, nonchalance, unconcern, dry eyes, insouciance, recklessness, callousness, heart of stone, stock and stone, marble, deadness, torpor, torpidity, obstupefaction, lethargy, coma, trance, vegetative state, sleep, suspended animation, stupor, stupefaction, paralysis, palsy, numbness, neutrality, quietism, vegetation, insensible, unconscious, impassive, impassible, blind to, deaf to, dead to, unsusceptible, insusceptible, unimpressionable, unimpressible, passionless, spiritless, heartless, soulless, unfeeling, unmoral, apathetic, leuco-, phlegmatic, dull, frigid, cold blooded, cold hearted, cold as charity, flat, maudlin, obtuse, inert, supine, sluggish, torpid, torpedinous, torporific, sleepy, languid, half-hearted, tame, numbed, comatose, anaesthetic, stupefied, chloroformed, drugged, stoned, palsy-stricken, indifferent, lukewarm, careless, mindless, regardless, inattentive, neglectful, disregarding, unconcerned, nonchalant, pococurante, insouciant, sans souci, unambitious, unaffected, unruffled, unimpressed, uninspired, unexcited, unmoved, unstirred, untouched, unshocked, unstruck, unblushing, unanimated, vegetative, callous, thick-skinned, hard-nosed, pachydermatous, impervious, hardened, inured, casehardened, steeled against, proof against, imperturbable, unfelt, insensibly, aequo animo, without being moved, without being touched, without being impressed, in cold blood, with dry eyes, with withers unwrung, never mind, macht nichts, it is of no consequence, it cannot be helped, nothing coming amiss, it is all the same to, it is all one to.

N  physical inertness, inertness, dullness, inertia, vis inertiae, inertion, inactivity, torpor, languor, quiescence, latency, inaction, passivity, mental inertness, sloth, inexcitability, irresolution, obstinacy, permanence, rare gas, paraffin, noble metal, unreactivity, inert, inactive, passive, torpid, sluggish, dull, heavy, flat, slack, tame, slow, blunt, unreactive, lifeless, dead, uninfluential, latent, dormant, smoldering, unexerted, inactively, in suspense, in abeyance.

N  dullness, heaviness, flatness, infestivity &c, stupidity want of originality, dearth of ideas, prose, matter of fact, heavy book, conte a dormir debout, platitude, dull, dull as ditch water, unentertaining, uninteresting, flat, dry as dust, unfunny, unlively, logy, unimaginative, insulse, dry as dust, prosy, prosing, prosaic, matter of fact, commonplace, pedestrian, pointless, weary stale flat and unprofitable, stupid, slow, flat, insipid, vapid, humdrum, monotonous, melancholic, stolid plodding, boring, tiresome, tedious, davus sum non Aedipus, deadly dull and boring, DDB.

area of cardiac dullness