1. a door at the rear of a house, building, etc.
2. a secret, furtive, or illicit method, manner, or means.
Pronunciation: (bak'dôr', -dōr'), [key]
secret; furtive; illicit; indirect. Also,back'-door'.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.