con•tra•val•la•tion(kon′trə və lā′shən),USA pronunciationn.[Fort.]
a more or less continuous chain of redoubts and breastworks raised by besiegers outside the line of circumvallation of a besieged place to protect the besiegers from attacks from the outside, as by a relieving force.
1670–80; contra-1 + vallation; compare French contrevallation, Italian contravvallazione