Any land or marine reptile of the order Testudines, characterised by a protective shell enclosing its body. See also tortoise.
2
(specifically) A marine reptile of that order.
3
An Ancient Roman attack method, where the shields held by the soldiers hide them, not only left, right, front and back, but also from above.
4
A type of robot having a domed case (and so resembling the reptile), used in education, especially for making line drawings by means of a computer program.