An entry at the rear of a building, as in Deliveries are supposed to be made at the back door only. [First half of 1500s]
A clandestine, unauthorized, or illegal way of operating. For example, Salesmen are constantly trying to push their products by offering special gifts through the back door. This term alludes to the fact that the back door cannot be seen from the front. [Late 1500s]
Dictionary.com presents 366 FAQs, incorporating some of the frequently asked questions from the past with newer queries.