noun
deputy head; vice chief; deputy director
General term for the second-in-command in an organization, team, or department.
彼は消防団の副長を務めている。
He serves as the deputy chief of the volunteer fire corps.
副長が会議の進行を引き継いだ。
The vice chief took over the proceedings of the meeting.
noun
Specific naval term for the second-in-command of a ship or unit.
艦長が不在のときは副長が指揮を執る。
When the captain is absent, the executive officer takes command.
Compound of 副 (vice-, deputy) and 長 (chief, head).