person who is enlisted in a branch of the armed force
United States Armed Forces oath of enlistment Upon enlisting in the United States Armed Forces, each person enlisting in an armed force (whether a soldier, sailor, coast guardsman, airman, or Marine) takes an oath of enlistment required by federal statute in 10 U.S.C. § 502. That section provides the text of the oath and sets out who may administer the oath:
Commander (United States) In the United States Navy, the United States Coast Guard, the United States Public Health Service Commissioned Corps, and the National Oceanic and Atmospheric Administration Commissioned Officer Corps, commander (abbreviated "CDR") is a mid-grade officer rank, with the pay grade of O-5. Commander ranks above lieutenant commander (O-4) and below captain (O-6). Commander is equivalent to the rank of lieutenant colonel in the other uniformed services.[2] Notably, it is the first rank at which the holder wears an embellished cap, whereas officers of the other services are entitled to embellishment at O-4 rank. Promotion to commander in the US Navy is governed by Department of Defense policies derived from the Defense Officer Personnel Management Act (DOPMA) of 1980 or its companion Reserve Officer Personnel Management Act (ROPMA). DOPMA/ROPMA guidelines suggest that 70% of lieutenant commanders should be promoted to commander after serving a minimum of three years at their present rank and after attaining 15-17 years of cumulative commissioned service, although this percentage may vary and be appreciably less for certain officer designators (i.e., primary "specialties") dependent on defense budgets, force structure and needs of the service.