from
The Collaborative International Dictionary of English v.0.48
Trapdoor \Trap"door`\, n.
1. (Arch.) A lifting or sliding door covering an opening in a
roof or floor.
[1913 Webster]
2. (Mining) A door in a level for regulating the ventilating
current; -- called also {weather door}. --Raymond.
[1913 Webster]
{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 ({Cteniza
Californica}).
[1913 Webster]