Postern — Defs

01 n. Originally, a back door or gate; a private entrance; hence, any small door or gate.

1.
Originally, a back door or gate; a private entrance; hence, any small door or gate.
“He by a privy postern took his flight.” — Spenser.

“Out at the postern, by the abbey wall.” — Shak.
2.
A subterraneous passage communicating between the parade and the main ditch, or between the ditches and the interior of the outworks.(Fort.)

02 a. Back; being behind; private.