Trap″door′ (?), n. 1. (Arch.) A lifting or sliding door covering an opening in a roof or floor.
2. (Mining) A door in a level for regulating the ventilating current; — called also weather door. Raymond.
Trapdoor spider(Zoöl.), any one of several species of large spiders which make a nest consisting of a vertical hole in the earth, lined with a hinged lid, like a trapdoor. Most of the species belong to the genus Cteniza, as the California species (C. Californica).