Bright

Antonyms of bright:
dim, dimmed, dull, unhappy, lacklustre, mat, matte, inglorious, unintelligent, unfortunate, unpolished, colourless, matted, colorless, subdued, nonresonant, lustreless, flat, inauspicious, unreverberant, dark, lusterless, soft, stupid, matt, lackluster, awkward, clumsy, foolish, ignorant, slow, thick-headed, bungling, idiotic, senseless, witless, blackened, darkened, darkish, darkling, darksome, dusky, gloomy, lightless, murky, obscure, obscured, pitch-black, pitch-dark, somber, sunless, tenebrous, unlit, cloudy, shadowlike, shadowy, shady, gray, leaden, pale, palish, unbright, unbrilliant, lightproof, dusk, joyless, sad, unsatisfied, lethargic, listless, sluggish, torpid, blue, brokenhearted, crestfallen, dejected, depressed, despondent, disconsolate, disheartened, down, downcast, downhearted, droopy, forlorn, hangdog, heavyhearted, inconsolable, low, low-spirited, melancholy, mirthless, sorrowful, dour, glum, morose, saturnine, sulky, sullen, feebleminded, simpleminded, boobish, half-baked, imbecile, moronic, silly, illiterate, lowbrow, nonintellectual, unacademic, uneducated, uninformed, unintellectual, untaught, unthinking, absurd, asinine, balmy, cockeyed, crackpot, crazy, cuckoo, daffy, daft, dippy, dotty, featherheaded, fool, harebrained, insane, kooky, loony, lunatic, mad, nonsensical, nutty, preposterous, sappy, screwball, tomfool, unwise, wacky, zany, airheaded, birdbrained, boneheaded, brain-dead, brainless, bubbleheaded, chuckleheaded, dense, dim-witted, doltish, dopey, dorky, dumb, dunderheaded, empty-headed, fatuous, gormless, half-witted, knuckleheaded, lamebrain, lunkheaded, mindless, obtuse, opaque, pinheaded, simple, slow-witted, softheaded, thick, thickheaded, thick-witted, unsmart, vacuous, weak-minded, cheerless, comfortless, doubtful, dubious, uncertain, bearish, grim, negative, unfavorable, funereal, miserable, wretched, bleak, depressing, desperate, discouraging, disheartening, dismal, downbeat, dreary, hopeless, pessimistic, unencouraging, unlikely, unpromising, unpropitious, unlucky, calamitous, catastrophic, disastrous, fatal, ruinous, baleful, dire, direful, doomy, foreboding, ill, ill-boding, menacing, minatory, ominous, portentous, sinister, threatening, futureless, drab, black, desolate, dispiriting, insignificant, minor, unimportant, average, inferior, mediocre, uncelebrated, unsung, blank, stoic, unemotional, darkening, frowning, glaring, glowering, lowering, scowling, harsh, inclement, severe, blustering, blustery, breezy, gusty, foggy, hazy, misty, soupy, dirty, foul, nasty, overcast, rainy, raw, rough, squally, stormy, tempestuous, turbulent.
Examples of usage:
  1. How bright they were!
    "Thelma", Marie Corelli.
  2. By the way a bright thought occurred.
    "Curiosities of Impecuniosity", H. G. Somerville.
  3. In the fall of 1775 all seemed to be bright with hope.
    "The Old Franciscan Missions Of California", George Wharton James.