A dungeon feature is a physical fixture in a dungeon with some kind of interesting use, functionality, or effect. Every one is different, but each adds flavor and interest to the environment.
“A fountain is a dungeon feature found throughout the dungeon. Players may drink from the...Fountain
“Traps are dungeon features which appear on the floor of the dungeon, invisible until triggered...Traps
“Vendors (aka Traders or Merchants) are any of the neutral NPC's found throughout the dungeon...Traders
“Room found on the lowest level of the Gnomish Mines behind a locked door. Requires a gold key to...Wine Cellar