testudo
noun
tes·tu·do te-ˈstü-(ˌ)dō 
-ˈtyü-
plural testudos
: a cover of overlapping shields or a shed wheeled up to a wall used by the ancient Romans to protect an attacking force
Word History
Etymology
Latin testudin-, testudo, literally, tortoise, tortoise shell; akin to Latin testa shell
First Known Use
1609, in the meaning defined above