Definitions

1. noun

A small door or gate, especially one in a castle wall.

“The postern was used for secret entrances and exits during times of war.”

2. noun

A side door or entrance to a building, especially a church.

“The postern of the old church led to a quiet garden.”

3. noun

A side door or passage in a building, especially a castle, that is used as a means of escape or access.

“The postern allowed the king to leave the castle undetected.”