engine

Engine comes from Middle English engyn, borrowed from Anglo-Norman engine and Old French engin, meaning skill, cleverness, or a war machine. That word traces back to Latin ingenium, meaning innate quality, nature, or genius — itself connected to ingignō, to implant or produce by birth.

The word started out pointing to a person's inborn talent or cunning, then narrowed to the clever contraptions that talent could build — first war machines like the battering ram, later the mechanical engines we know today.

It shares its Latin root, ingenium, with ingenious — so calling someone ingenious and calling a machine an engine both go back to the same idea of innate cleverness. Engineer, the person who builds and runs such machines, comes from the same family.