JDAM

The Joint Direct Attack Munition (JDAM) is a low-cost guidance kit that converts existing unguided gravity bombs, or "dumb bombs", into accurate, all-weather "smart" munitions. JDAM equipped bombs are guided to their target by an integrated inertial guidance system coupled with a Global Positioning System (GPS) receiver for enhanced accuracy, giving them a published range of up to 15 nautical miles from the release point. JDAM is a joint United States Air Force and United States Navy program. It is in service with the U.S. Air Force, U.S. Navy and the U.S. Marine Corps.
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Noun
1. a pinpoint bomb guidance device that can be strapped to a gravity bomb thus converting dumb bombs into smart bombs
(synonym) Joint Direct Attack Munition
(hypernym) guidance system, guidance device