What is "antemural"

Antemural \An`te*mu"ral\, n. [L. antemurale: ante + murus wall. See Mural.] An outwork of a strong, high wall, with turrets, in front of the gateway (as of an old castle), for defending the entrance.

n. An outwork of a strong, high wall, with turrets, in front gateway (as of an old castle), for defending the entrance.