contravallation Hear it!

contravallation Definition

con·tra·val·la·tion (kän′trə və lās̸hən)

noun

a fortification set up to protect a besieging force from attack by the defenders of the besieged place or by a relieving force from the outside

Etymology: Fr contrevallation < L contra, counter + vallatio, entrenchment < vallum, wall