from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A small rear gate, especially one in a fort or castle.
- adj. Situated in the back or at the side.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A back-gate, backdoor, side entrance, or other gateway distinct from the main entrance.
- n. By extension, a separate or hidden way in or out of a place, situation etc.
- adj. Situated at the rear; posterior.
from the GNU version of the Collaborative International Dictionary of English
- n. Originally, a back door or gate; a private entrance; hence, any small door or gate.
- n. A subterraneous passage communicating between the parade and the main ditch, or between the ditches and the interior of the outworks.
- adj. Back; being behind; private.
from The Century Dictionary and Cyclopedia
- n. A back door or gate; a private entrance; hence, any small door or gate. See cuts under castle and barbican.
- n. In fortification, a covered passage closed by a gate, usually in the angle of the flank of a bastion, or in that of the curtain, or near the orillion, descending into the ditch.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a small gate in the rear of a fort or castle
Middle English posterne, from Old French, alteration of posterle, from Late Latin posterula, diminutive of Latin posterus, behind; see posterior.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Late Latin posterna, and its likely sources, Anglo-Norman posterne, Old French posterne, alteration of posterle, from Late Latin posterula ("back door"), from Latin posterus ("later"). (Wiktionary)