a genus of tortoises which formerly included a large number of diverse forms, but is now restricted to certain terrestrial species, such as the european land tortoise (testudo graeca) and the gopher of the southern united states.-a cover or screen which a body of troops formed with their shields or targets, by holding them over their heads when standing close to each other. this cover resembled the back of a tortoise, and served to shelter the men from darts, stones, and other missiles. a similar defense was sometimes formed of boards, and moved on wheels.-a kind of musical instrument. a species of lyre; -- so called in allusion to the lyre of mercury, fabled to have been made of the shell of a tortoise.