n. | 1. | Originally, a back door or gate; a private entrance; hence, any small door or gate. |
2. | (Fort.) A subterraneous passage communicating between the parade and the main ditch, or between the ditches and the interior of the outworks. | |
a. | 1. | Back; being behind; private. |
Noun | 1. | postern - a small gate in the rear of a fort or castle |