water scorpion

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

• noun Any of various aquatic predatory insects of the family Nepidae, having a long breathing tube projecting from the end of the abdomen.

from The Century Dictionary.

• noun A large aquatic and carnivorous bug of the family Nepidæ. See Nepa.

from the GNU version of the Collaborative International Dictionary of English.

• (Zoöl.) See nepa.

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

• noun any long-legged aquatic insect of the family Nepidae, especially the species Nepa cinerea.

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

• noun long-legged aquatic insect having the front legs fitted for seizing and holding prey and the abdomen extended by a long breathing tube