Why this word is great
NIGRESCENCE — [Noun] The process of becoming black or dark; blackening. From Latin nigrescens, present active participle of nigrescō ("to become black"), from nigrēre ("to be black") + -escence (denoting a process or state). Unlike "melanization" (which narrows to biological pigment) or "ebonization" (which gilds darkness with metaphor), nigrescence is the quiet, inexorable work of shadow itself. It is the slow creep of tarnish across silver, the bruise deepening under skin, the way a stormcloud thickens until it snuffs out the horizon—a reminder that darkness is not an absence, but a patient, inevitable arrival.