claymore mine

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

• noun A lens-shaped, ground-emplaced antipersonnel mine whose blast is focused in the direction of the oncoming enemy.

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

• noun (Mil.) an antipersonnel land mine designed to produce a high-velocity spray of steel fragments in a relatively narrow fan-shaped cone, directed toward the enemy. They are usually detonated by an electrical remote control.

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

• noun an antipersonnel land mine whose blast is aimed at the oncoming enemy