testudo
/tesˈtjuːdəʊ/noun
(pl. testudos 或testudines /-dɪniːz/)
1- (in ancient Rome) a screen on wheels and with an arched roof, used to protect besieging troops（古罗马用于保护攻城军队而装于车轮上的）穹形护顶。
1.1
- a protective screen formed by a body of troops holding their shields above their heads in such a way that the shields overlap（由一队士兵举盾围成的）龟甲形连环盾。
词源
late Middle English: from Latin， literally 'tortoise'， from testa 'tile， shell'.