1. the person who holds the secretaryship of the Defense Department - the first Defense Secretary was James V. Forrestal who was appointed by Truman • Syn: Defense Secretary • Hypernyms: secretary 2. the position of the head of the Department of Defense - the position of Defense Secretary was created in 1947 • Syn: Defense Secretary • Hypernyms: secretaryship • Member Holonyms: United States Cabinet, US Cabinet