box turtle

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of several chiefly terrestrial turtles of the genus Terrapene of North America, having a domed carapace and a hinged bottom shell that pulls up against the carapace, allowing the animal to become completely encased within its shell.
• noun Any of various terrestrial or aquatic turtles of the genera Cuora and Pyxidea of China and Southeast Asia, having a similar appearance to American box turtles.

from The Century Dictionary.

• noun The common name in the United States of the box-tortoise.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A turtle of the genus Terrapene (the North American box turtles), or of Cuora or Pyxidea (the Asian box turtles), characterised by having a domed shell that is hinged at the bottom, allowing the animal to close its shell tightly to escape predators.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun chiefly terrestrial turtle of North America; shell can be closed tightly