Defense Health Agency. The Defense Health Agency (DHA) is a joint, integrated Combat Support Agency that enables the U.S Army, U.S Navy, and U.S Air Force medical services to provide a medically ready force and ready medical force to Combatant Commands in both peacetime and wartime.
Definition of preemption. 1a : the right of purchasing before others; especially : one given by the government to the actual settler upon a tract of public landb : the purchase of something under this right.
Definition of presumption for English Language Learners. : 1  a belief that something is true even though it has not been proved. 2  law : an act of accepting that something is true until it is proved not true. : 3  willingness to do something without the right or permission to do it.