cluster bomb

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

• noun A projectile that, when dropped from an aircraft or fired through the air, releases explosive fragments over a wide area.

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

• noun Explosive munition designed to explode in the air and release a cluster of smaller explosives, thus spreading the blast over a larger area.

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

• noun bomb consisting of a canister that is dropped from a plane and that opens to release a cluster of bomblets (usually fragmentation bombs) over a wide area