noun
petty officer third class (USN)
A specific rank in the U.S. Navy, equivalent to E-4. Used in military contexts.
彼は三等兵曹に昇進した。
He was promoted to petty officer third class.
Compound of 三等 (third class) and 兵曹 (military officer). The term is a direct translation of the U.S. Navy rank.