an officer in the armed forces holding rank by a commission: the lowest rank in the U.S. Army, Air Force, and Marine Corps is second lieutenant; in the Navy and Coast Guard, ensign
See commissioned officer in American Heritage Dictionary 4
(kə-mĭshˈənd)
noun
An officer who holds a commission and ranks as a second lieutenant or above in the U.S. Army, Air Force, or Marine Corps, or as an ensign or above in the U.S. Navy or Coast Guard.