The road to Zork began in late May of 1977, when Dave Lebling put together a very simple parser and game engine quite similar to Adventure’s, from which Marc Blank and Tim Anderson built their first four-room game as a sort of proof of concept. … The name itself was a nonsense word floating around MIT that one might use in place of something, shall we say, stronger in stressful situation: “Zork the bloody thing!” when a piece of code just wouldn’t work correctly, etc. The file holding the game-in-progress got named “Zork” as a sort of placeholder until someone came up with something better. In the case of Zork, though, a proper name was slow in coming. And so Zork the game remained for the first six months of its existence. …
At some point around the fall of 1977, the DMG hackers had decided that their creation really, really needed a “proper” name. Lebling suggested Dungeon, which excited no one (Lebling included), but no one could come up with anything better. And so Dungeon it was. … Shortly after that, MIT heard legal rumblings from, of all places, TSR, publishers of Dungeons and Dragons – and of a dungeon-crawling board game called simply Dungeon! TSR was always overzealous with lawsuits, and the consensus amongst the MIT lawyers that the DMG hackers consulted was that they didn’t have a legal leg to stand on. However, rather than get sucked into a lengthy squabble over a name none of them much liked in the first place, they decided to just revert to the much more memorable Zork. And so by the beginning of 1978 Dungeon became Zork once more, and retained that name forevermore.
–Jimmy Maher, Zork on the PDP-10