snapping turtle

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

• noun Any of several large freshwater turtles of the family Chelydridae of the Americas, having a rough shell and powerful hooked jaws that close with a snap, especially the common North American species Chelydra serpentina and the alligator snapping turtle of the south-central United States.

from The Century Dictionary.

• noun The alligator-terrapin or alligator-tortoise, Chelydra serpentina, a large and ferocious turtle of the United States: so called from the way it snaps its jaws to bite; a snapper.

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

• noun Any of several large American freshwater turtles of the family Chelydridae; they have powerful hooked jaws that close with a snap.

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

• noun large aggressive freshwater turtle with powerful jaws