abatis
abutment
advanced work
aegis
arc-boutant
arch dam
arm guard
backstop
balistraria
bamboo curtain
bank
banquette
bar
barbed-wire entanglement
barbican
barrage
barricade
barrier
bartizan
bastion
battlement
beam
bear-trap dam
beaver dam
boom
breakwater
breastwork
brick wall
buffer
bulkhead
bumper
buttress
buttress pier
buttressing
casemate
cheval-de-frise
circumvallation
citadel
cofferdam
contraceptive
contravallation
copyright
counterscarp
cover
crash helmet
curtain
cushion
dam
dashboard
defend
bulwarked
bulwarking
bulwarks
balustrade
battlements
defence
defender
defenses
edifice
fortification
gangway
palisade
parapet
pillar
prop
rampart
redoubt
safeguard
sentinel
stronghold
upholder