engineer; engineering officer
Refers to a licensed engineer responsible for operating and maintaining engines, boilers, or machinery on trains, ships, or aircraft. In modern contexts, often replaced by more specific titles like 機関長 (chief engineer) or 運転士 (train operator), but still used in historical or formal settings.
He sailed around the world as a ship's engineer.
The steam locomotive engineer operated the train while shoveling coal.
Compound of 機関 (engine, machinery) and 士 (person with a certain qualification or occupation).