The term refers to the person who is in charge of the motor (of the electric car) in the same sense as a railroad engineer is in charge of the engine. The term was (and, where still used, is) gender-neutral. Though motormen have historically been male, females in the position (such as in the U.S. during the World Wars) were usually also called motormen as a job title.
The term has been replaced by more neutral ones, as gender-specific job titles have fallen into disuse, and because many systems employ large numbers of women in the position. On the New York Subway, the position is now called train operator (T.O.), but it is still called motorman in Chicago.
The term may also refer to a person on a locomotive-hauled train when the train is being propelled by the locomotive. The driver is responsible for applying power in the locomotive, while the motorman (usually in a specially-built or converted vehicle) at the front of the train, is responsible for obeying signals, sounding the horn, and applying the brakes where necessary.