Wiktionary
n. 1 A commissioned officer of the United States Navy whose rank is above an ensign's and below a lieutenant, or a corresponding rank in other navies. 2 A commissioned officer in the United States Coast Guard, Public Health Service, or National Atmospheric and Oceanic Administration whose rank is above an ensign and below a lieutenant.
WordNet
n. an officer holding a commissioned rank in the United States Navy or United States Coast Guard; below lieutenant and above ensign [syn: lieutenant JG]
Usage examples of "lieutenant junior grade".
When Hearnes private log came into evidence, she found that Hearne had described Lieutenant Junior Grade Suiza as competent but colorless.
The OOD and the new exec, a lieutenant junior grade who had previously commanded a yard minesweeper, stood at a respectful distance from the two commanding officers.