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rampart

[ram-pahrt, -pert] / ˈræm pɑrt, -pərt /
NOUN
fortification, stronghold
Synonyms
STRONGEST
barricade
STRONG
barrier bastion breastwork bulwark defense earthwork elevation embankment fence fort guard hill mound parapet protection ridge security support wall
WEAK
vallation
Antonyms
STRONG
depression ditch

From Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.