adverb, adverb taking the 'to' particle, noun
Describes something that is intensely, vividly black. Often used with と or as an adverbial phrase to modify verbs like 光る, 輝く, or 染まる.
彼の髪は黒々と輝いていた。
His hair shone deep black.
夜空に黒々とした雲が広がった。
Jet-black clouds spread across the night sky.
真っ黒 means 'pitch black' or 'completely black', often implying a solid, uniform blackness. 黒々 emphasizes a vivid, lustrous, or intense black quality, often with a sense of depth or sheen.
Reduplication of 黒 (くろ, 'black') with the suffix 々, forming an adverb/noun that intensifies the meaning to 'deeply black'.