A door on the floor or ground, oftentimes in a castle, which can be lifted to reveal a tunnel or chamber. Sometimes concealed by being made to look like the floor, hidden under a rug, located in a secret room, or otherwise hidden so that it will only be found by those who know of its existence and location. Some trapdoors lead to a storm cellar for protection from tornadoes, but the more commonly thought of trapdoors are those from the middle ages. They were oftentimes entrances to dungeons where prisoners were kept, cellars where food and drinks were kept, or tunnel networks leading away from a castle that allowed castle residents to escape in the event of siege.
'Hey Liz, want to go explore that old castle with me? If we get lucky we might even find the rumored trapdoor! Then we can find the treasure in the dungeon underneath.' -Dylan
'Yeah, I'd love to! Can Josie come too?' -Liz
'Yes, of course, I was going to ask her!' -Dylan
'Awesome, this is going to be so fun! I love exploring secret trapdoors!' -Josie