Chiefly terrestrial turtle of North America; shell can be closed tightly WordNet 3.0 & Open English WordNet

Box turtle is the common name for several species of turtle. Wikipedia

A turtle of the genus Terrapene (the North American box turtles), 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. Wiktionary