1.  blackness(n = noun.attribute) black, inkiness - the quality or state of the achromatic color of least lightness (bearing the least resemblance to white);
is a kind of achromatic color, achromatic colour
has particulars: coal black, ebony, jet black, pitch black, sable, soot black
Derived forms adjective black₁, adjective black₁₄, adjective black₁₃

2.  blackness(n = noun.state) black, lightlessness, pitch blackness, total darkness - total absence of light; "they fumbled around in total darkness"; "in the black of night"
is a kind of dark, darkness
Derived form adjective black₈

   The quality or state of being black; black color; atrociousness or enormity in wickedness. [1913 Webster]
"They're darker now than blackness." [1913 Webster]

N  darkness, absence of light, blackness, obscurity, gloom, murk, dusk, Cimmerian darkness, Stygian darkness, Egyptian darkness, night, midnight, dead of night, witching hour of night, witching time of night, blind man's holiday, darkness visible, darkness that can be felt, palpable obscure, Erebus, the jaws of darkness, sablevested night, shade, shadow, umbra, penumbra, sciagraphy, obscuration, occultation, adumbration, obumbration, obtenebration, offuscation, caligation, extinction, eclipse, total eclipse, gathering of the clouds, shading, distribution of shade, chiaroscuro, noctivagation, black body, hohlraum, black hole, dark star, dark matter, cold dark matter, dark, darksome, darkling, obscure, tenebrious, sombrous, pitch dark, pitchy, pitch black, caliginous, black, sunless, lightless &c (sun) (light), somber, dusky, unilluminated &c (illuminate), nocturnal, dingy, lurid, gloomy, murky, murksome, shady, umbrageous, overcast, cloudy, darkened, dark as pitch, dark as a pit, dark as Erebus, benighted, noctivagant, noctivagous, in the dark, in the shade, brief as the lightning in the collied night, eldest Night and Chaos, ancestors of Nature, the blackness of the noonday night, the prayer of Ajax was for light.

pitch blackness