THESAURUS
darken
attaint, bandage, beat down, becloud, bedarken, bedaub, bedazzle, bedim, befog, begloom, bemist, benight, besmear, besmirch, besmoke, bestain, black, black out, blacken, blackwash, blanch, blind, blind the eyes, blindfold, block the light, blot, blot out, blotch, blur, blush, brand, brown, cast a shadow, cast down, change color, charcoal, clabber up, cloud, cloud over, cloud up, color, cork, crimson, damp, dampen, dampen the spirits,
darken over, darkle, dash, daub, daze, dazzle, deject, denigrate, depress, deprive of sight, dim, dim out, dinge, dirty, discolor, discourage, dishearten, dispirit, dusk, ebonize, eclipse, encloud, encompass with shadow, enmist, excecate, flush, fog, glare, gloam, gloom, glow, gouge, grow dark, grow dim, haze, hoodwink, ink, knock down, look black, lower, lower the spirits, make blind, mantle, mark, melanize, mist, murk, nigrify, nubilate, obfuscate, obnubilate, obscure, obumbrate, occult, occultate, opaque, oppress, overcast, overcloud, overshadow, oversmoke, pale, press down, redden, sadden, scorch, sear, shade, shadow, singe, sink, slubber, slur, smear, smirch, smog, smoke, smudge, smut, smutch, snow-blind, soil, somber, soot, strike blind, taint, tarnish, turn color, turn pale, turn red, weigh heavy upon, weigh upon, whiten
ROGET THESAURUS
darken
Darkness
VB
be dark,
darken, obscure, shade, dim, tone down, lower, overcast, overshadow, eclipse, obfuscate, offuscate, obumbrate, adumbrate, cast into the shade becloud, bedim, bedarken, cast a shade, throw a shade, spread a shade, cast a shadow, cast a gloom, throw a shadow, spread a shadow, cast gloom, throw gloom, spread gloom, extinguish, put out, blow out, snuff out, doubt, turn out the lights, douse the lights, dim the lights, turn off the lights, switch off the lights.
Dimness
VB
be dim, grow dim, flicker, twinkle, glimmer, loom, lower, fade, pale, pale its ineffectual fire, render dim, dim, bedim, obscure,
darken, tone down.
Blackness
VB
be black, render black, blacken, infuscate, denigrate, blot, blotch, smutch, smirch,
darken, black, sable, swarthy, somber, dark, inky, ebony, ebon, atramentous, jetty, coal-black, jet-black, fuliginous, pitchy, sooty, swart, dusky, dingy, murky, Ethiopic, low-toned, low in tone, of the deepest dye, black as jet, black as my hat, black as a shoe, black as a tinker's pot, black as November, black as thunder, black as midnight, nocturnal, nigrescent, gray, obscure.
Unintelligibility
VB
be unintelligible, require explanation, have a doubtful meaning, pass comprehension, render unintelligible, conceal,
darken, confuse, perplex, not understand, lose, lose the clue, miss, not know what to make of, be able to make nothing of, give it up, not be able to account for, not be able to make either head or tail of, be at sea, wonder, see through a glass darkly, not understand one another, play at cross purposes.