Counterfort

Counterfort
From LoveToKnow 1911
COUNTERFORT (Fr. contrefort), in architecture, a buttress or pier built up against the wall of a building or terrace to strengthen it, ...

Counterfort: An inner buttress used to strengthen the masonry of a ramparts revetment.

Counterfort - defence work of besieging force.
Counterguard - a long, near-triangular freestanding fortification within the moat.
Counterscarp - outer slope of a ditch.
Course - level layer of stones or bricks.

See also: Thrust, Pier, Architecture, Buttress, Wing