1. postern - Noun
2. postern - Adjective
Originally, a back door or gate; a private entrance; hence, any small door or gate.
A subterraneous passage communicating between the parade and the main ditch, or between the ditches and the interior of the outworks.
Back; being behind; private.
Source: Webster's dictionaryAn eighth unnamed 'portal' gate (smaller than a postern gate) existed in the wall just to the northwest of the castle, now in the gardens of Castle Walk House. Source: Internet
From this and other surviving documents it seems that the town walls and gates were in place by 1270. citation They were constructed about the central part of the community with four main gates and three postern gates. Source: Internet
There is a small postern gate at L. The enceinte comprises two large open courts, surrounded with buildings connected with cloister galleries of wood or stone. Source: Internet