General Definition: 1. An object which is flat on top and has a opening flap (also flat), or any thing or any object that is directly or indirectly associated with this, especially a trapdoor or hatch. As a Noun: 1. A small horizontal door in a floor, ceiling, or stage. English = trapdoor. 2. An opening in a deck of a ship, which is used for people to come on deck or go below, or during loading and unloading cargo. English = hatch.