Lieutenant (United States)
The military rank of lieutenant, in the United States Navy, United States Coast Guard, National Oceanic and Atmospheric Administration Commissioned Officer Corps (NOAA-COO), and United States Public Health Service Commissioned Corps (PHS-CC), the rank of lieutenant is divided between:
- Lieutenant (O-3), equivalent to a Captain in the U.S. Army, Air Force & Marines
- Lieutenant junior grade (O-2), sometimes referred as "lieutenant j.g."
In the United States Army, Air Force, and Marine Corps is divided between:
- First lieutenant (O-2), sometimes called simply "lieutenant"
- Second lieutenant (O-1), equivalent to an Ensign in the Navy, Coast Guard, NOAA-COO & PHS-CC
During the American Civil War (1861-1865), brevet second lieutenants in the Union Army and Confederate States Army were sometimes also known as "third lieutenants".