defensive structure

Từ điển WordNet v3.1 - WordNet Dictionary

noun

a structure used to defend against attack
- the artillery battered down the defenses
• Syn:
defense, defence
• Hypernyms:
structure, construction
• Hyponyms:
cheval-de-frise, chevaux-de-frise, fortification, munition, fortress,
fort, line of defense, line of defence, outwork, stronghold, fastness