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 Zool., 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).
© Webster 1913.