Quote from egnor on 25 July 2020, 11:57 pm

This was tricky! Some hints for those still stuck...

Hint 1: [spoiler]The answer is a singular 7 letter noun.[/spoiler]

Hint 2: [spoiler]The word is especially meaningful for the pair "dark" and light", or other visual differences.[/spoiler]

Hint 3: [spoiler]The term is often used in art or photography to describe adjacent but very different things.[/spoiler]