Testudines

Turtles, Tortoises, and Terrapins are reptiles of the Order Testudines (all living turtles belong to the crown group Chelonia), most of whose body is shielded by a special bony or cartilagenous shell developed from their ribs. The Order Testudines includes both extant (living) and extinct species, the earliest known turtles being from around 215 million years ago, making turtles one of the oldest reptile groups, and a much more ancient group than  lizards and snakes. About 300 species are alive today; some are highly endangered. Turtles are ectothermic.
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(pl. )
of Testudo
  

Noun
1. tortoises and turtles
(synonym) Chelonia, order Chelonia, Testudinata, order Testudinata, order Testudines
(hypernym) animal order
(member-holonym) Anapsida, subclass Anapsida
(member-meronym) chelonian, chelonian reptile