Tor·toise n.
 1. Zool. Any one of numerous species of reptiles of the order Testudinata.
 Note: ☞ The term is applied especially to the land and fresh-water species, while the marine species are generally called turtles, but the terms tortoise and turtle are used synonymously by many writers.  See Testudinata, Terrapin, and Turtle.
 2. Rom. Antiq. Same as Testudo, 2.
 Box tortoise, Land tortoise, etc. See under Box, Land, etc.
 Painted tortoise. Zool. See Painted turtle, under Painted.
 Soft-shell tortoise. Zool. See Trionyx.
 Spotted tortoise. Zool. A small American fresh-water tortoise (Chelopus guttatus or Nanemys guttatus) having a blackish carapace on which are scattered round yellow spots.
 Tortoise beetle Zool., any one of numerous species of small tortoise-shaped beetles.  Many of them have a brilliant metallic luster.  The larvae feed upon the leaves of various plants, and protect themselves beneath a mass of dried excrement held over the back by means of the caudal spines.  The golden tortoise beetle (Cassida aurichalcea) is found on the morning-glory vine and allied plants.
 Tortoise plant. Bot. See Elephant's foot, under Elephant.
 Tortoise shell, the substance of the shell or horny plates of several species of sea turtles, especially of the hawkbill turtle. It is used in inlaying and in the manufacture of various ornamental articles.
 Tortoise-shell butterfly Zool., any one of several species of handsomely colored butterflies of the genus Aglais, as Aglais Milberti, and Aglais urticae, both of which, in the larva state, feed upon nettles.
 Tortoise-shell turtle Zool., the hawkbill turtle. See Hawkbill.

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 Tri·on·yx n.  Zool. A genus of fresh-water or river turtles which have the shell imperfectly developed and covered with a soft leathery skin.  They are noted for their agility and rapacity.  Called also soft tortoise, soft-shell tortoise, and mud turtle.
 Note: ☞ The common American species (Trionyx ferox syn. Aspidonectus ferox) becomes over a foot in length and is very voracious.  Similar species are found in Asia and Africa.

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