con·vert·er / kənˈvərtər/ (also con·ver·tor) • n. a person or thing that converts something. ∎ a device for altering the nature of an electric current or signal, esp. from AC to DC or vice versa, or from analog to digital or vice versa. ∎ a retort used in steelmaking. ∎ short for catalytic converter. ∎ Comput. a program that converts data from one format to another. ∎ a camera lens that changes the focal length of another lens by a set amount.