All good Dungeons deserve a good name. Locally there's a town called Netherton where Nether- means down/lower and comes to English from the Old English nitera. There's also a suburb of Netherton named Netherend and the first time I ever came across the name (on a street sign sighted from within the bus I was on) I immediately thought it redolent of fairy tales and mythology. Netherend is actually quite a common village name in England and also often used to refer to the outskirts or last few buildings of a village. In the town where I grew up there was an area known as "Townsend" which no longer was the end of the town due to heavy post-war development.
I've always liked the double meaning of the word 'pit' when used in the Dungeon sense. Obviously a pit is a hole in the ground but from a D&D point of view it's a common trap. There's also the Biblical meaning referring to hell and locally in the Black Country it refers to a mine - once again returning us to subterraean passages and chambers with all the attendant hazards and fears.
Concatanate them together and we got Netherpit - a great name for a Dungeon.