Merriam-Webster's Collegiate® Dictionary, 11th Edition
TURTLE
I. noun
Etymology: Middle English, from Old English turtla, from Latin turtur Date: before 12th century turtledove ,
II. noun (plural turtles; also turtle)
Usage: often attributive
Etymology: modification of French tortue, from Late Latin (bestia) tartarucha, feminine of tartaruchus of Tartarus, from Greek tartarouchos, from Tartaros Tartarus; from Mithraic and early Christian association of the turtle with infernal forces
Date: 1612
any of an order (Testudines syn. Chelonia) of terrestrial, freshwater, and marine reptiles that have a toothless horny beak and a shell of bony dermal plates usually covered with horny shields enclosing the trunk and into which the head, limbs, and tail usually may be withdrawn,
III. noun
Date: 1952
turtleneck