Inky means as black as writing fluid. Inky darkness, an inky sky, inky fingers.
It carries depth as well as darkness — inky black is blacker than black, which is why the word suits night skies and deep water. It also means stained with ink. Note ink plus the -y ending that makes adjectives.
1adjectiveinkyAs black as ink.
“We walked home under an inky sky with no moon.”
inky is a quality of blackness.
Middle English
ynke
English
ink
English, today
inky
Built from
From ink + -y. ink comes from Middle English ynke. From Middle English ynke, from Old French enque, from Latin encaustum (“purple ink used by Roman emperors to sign documents”), from Ancient Greek ἔγκαυστον (“burned-in”), from ἐν (“in”) + καίω (“burn”). In this sense, displaced native blæc. Sense four refers to the ink used in newspapers.
Etymology from Wiktionary, CC BY-SA