Толковый словарь английского языка - commutator

noun Date: 1880 a series of bars or segments so connected to armature coils of a generator or motor that rotation of the armature will in conjunction with fixed brushes result in unidirectional current output in the case of a generator and in the reversal of the current into the coils in the case of a motor, an element of a mathematical group that when used to multiply the product of two given elements either on the right side or on the left side but not necessarily on both sides yields the product of the two given elements in reverse order