The word 'tanker' is a straightforward English compound formed in the late 19th century. Its root, 'tank', entered English in the early 17th century from the Gujarati word 'ṭāṅk' or Portuguese 'tanque', originally meaning an artificial pond or reservoir. The agent suffix '-er', of Old English origin, was appended to create a noun denoting a vehicle or vessel specifically designed to carry a tank or its contents. The term's logic is transparent: a 'tanker' is literally 'that which carries a tank', evolving from a general container to specialized transport for liquids like oil, and later, by analogy, to the soldiers operating armored 'tanks'.

Structure: tank (container) + er (agent suffix) - tank (origin: Gujarati/Poruguese; role: root, meaning a large container for liquid or gas) - er (origin: Old English; role: agent suffix, denoting a person or thing that performs an action or is associated with something)