\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} (Zo["o]l.), 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}).