engine (n.)

c. 1300, "mechanical device," especially one used in war; "manner of construction," also "skill, craft, innate ability; deceitfulness, trickery," from Old French engin "skill, wit, cleverness," also "trick, deceit, stratagem; war machine" (12c.), from Latin ingenium "innate qualities, ability; inborn character," in Late Latin "a war engine, battering ram" (Tertullian, Isidore of Seville). This is etymologically "that which is inborn," from in- "in" (from PIE root *en "in") + gignere "to beget, produce" (from PIE root *gene- "give birth, beget").

The sense of "device that converts energy to mechanical power" emerged in 18c. In 19c. the word was used especially of steam engines. Middle English also had ingeny (n.) "gadget, apparatus, device," directly from Latin ingenium.