Board Thread:Wiki discussions and announcements/@comment-25773000-20151104014443/@comment-3974211-20151117070426

Murder Bridge was chosen as a conjectural term for the map in light of the multiple skins available on that map: Butcher's Bridge and Howling Abyss. The term was chosen because the announcer in both maps will sometimes say "Welcome to Murder Bridge!" rather than the map's given name - so even if the term originates from the playerbase, it's reflected in game.

I digress that without Butcher's Bridge being playable - the term could be reverted. However, Riot has expressed plans to reintroduce the map by some means (player-favourite is to have it randomly selected on queue).