Subfusc
Adjective, chiefly British.
Drab, Dusky.
[Origin: Latin subfuscus brownish, dusky, from sub– + fuscus dark brown.]
(1710)
“Phelan straightened in the pew, then relaxed his spine against the seat’s backrest. He noticed that the church was growing darker around him, the shadows more subfusc. – The Ghosts of Sleath, James Herbert.
It can also mean formal clothing in some universities, which in the university context means wearing your gown and hood. In Oxford and Cambridge colleges you were considered naked if you appeared in hall, ie the dining room, without your gown.
Oh how interesting! I had no idea. Thanks.