Answer:

inkiest

Answer	Crossword Clue
INKIEST	As dark as possible
INKIEST	Most shadowy
INKIEST	Most murky

INKIEST	Superlatively black
INKIEST	Most pitch-black
INKIEST	Black to the max
INKIEST	Most like midnight

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.