aphotic (ay-FO-tik) adjective

Lightless, especially without sunlight.

[From Greek a- (not) + phot- (light). Ultimately from Indo-European
root bha- (to shine) that’s also the source of beacon, beckon, phantom,
phenomenon, and phosphorous.]

“I converted JBW’s office into an ultimate torture chamber by soundproofing and sealing any openings to make it truly an aphotic cube of hell”.