what is a third class petty officer
Freebase(0.00 / 0 votes)Rate this definition: Petty officer third class is the fourth enlisted rank in the U.S. Navy, U.S. Coast Guard, and the United States Naval Sea Cadet Corps, just above seaman and below petty officer second class, and is the lowest rank of non-commissioned officer, equivalent to a corporal in the U.S. Army and Marines.