Tortoise
late Middle English tortu, tortuce : from Old French tortue and Spanish tortuga, both from medieval Latin tortuca, of uncertain origin. The current spelling dates from the mid 16th century.
wiktionary
From Middle English tortuse, tortuce, tortuge, from Medieval Latin tortuca, of uncertain origin. May be from Late Latin tartarūcha, from tartarūchus, from Ancient Greek ταρταροῦχος(tartaroûkhos, “holder of Tartaros, Tartarus, the land of the dead in ancient stories”), because it used to be thought that tortoises and turtles came from the underworld and they were commonly paired with such infernal beasts; or from Latin tortus(“twisted”). Displaced native Old English byrdling.
etymonline
tortoise (n.)
1550s, altered (perhaps by influence of porpoise) from Middle English tortuse (late 15c.), tortuce (mid-15c.), tortuge (late 14c.), from Medieval Latin tortuca (mid-13c.), perhaps from Late Latin tartaruchus "of the underworld" (see Tartarus). Others propose a source in Latin tortus "twisted," based on the shape of the feet. The classical Latin word was testudo, from testa "shell." First record of tortoise shell as a pattern of markings is from 1782.
