engine [ME] Engine is from Old French engin, from Latin ingenium ‘talent, device’, the source also of ingenious [LME]. Like many English words that now start with en-, it could also be spelled in-. Its original senses were ‘ingenuity, cunning’, and ‘natural talent, wit, genius’, which survives in Scots as ingine [LME]. From there it became ‘the product of ingenuity, a plot, or snare’, and also ‘a tool or weapon’, specifically a large mechanical weapon, such as a battering ram or heavy catapult, constructed by engineers [ME]. By the mid 16th century something like our idea of an engine had arisen, a fairly complex device with moving parts that worked together.