Postern and Retral

Postern noun - A small gate in the rear of a fort or castle.

Retral and postern are semantically related In some cases you can use "Retral" instead an adjective "Postern".

Retral adjective - Moving or directed or tending in a backward direction or contrary to a previous direction.

Postern and retral are semantically related in back topic. Sometimes you can use "Postern" instead an adjective "Retral".