from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A cylindrical arrangement of insulated metal bars connected to the coils of a direct-current electric motor or generator, providing a unidirectional current from the generator or a reversal of current into the coils of the motor.
  • noun Mathematics In a commutative or noncommutative group, an element of the form ghg−1h−1 where g and h are elements of the group. If g and h commute, the commutator is the identity element.

from The Century Dictionary.

  • noun In electricity, that part of a continuous-current dynamo-electric machine which, by revolving in contact with the brushes, turns or directs the electrical actions in the armature coils of the machine so as to make the current and the voltage in the external circuit continuous.
  • noun In photography, a device for automatically effecting the exposure of a number of photographic plates at various predetermined instants during a total eclipse of the sun.
  • noun An apparatus used in connection with many electrical instruments for reversing the currents from the battery without changing the arrangement of the conductors from the poles: as, Bertin's commutator.
  • noun A contrivance for varying the strength of an electric current by bringing either a portion or the whole of the voltaic cells in a battery into the circuit.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Elec.) A piece of apparatus used for reversing the direction of an electrical current; an attachment to certain electrical machines, by means of which alternating currents are made to be continuous or to have the same direction. It may be attached to the end of the spindle of an electric motor, where a brush is in contact sequentially with the parts of the spindle that conduct current to the different windings of the motor.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun an electrical switch, in a generator or motor, that periodically reverses the direction of an electric current
  • noun mathematics (of a group) an element of the form ghg−1h−1 where g and h are elements of the group; it is equal to the group's identity if and only if g and h commute
  • noun mathematics (of a ring) an element of the form ab-ba, where a and b are elements of the ring, it is identical to the ring's zero element if and only if a and b commute

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun switch for reversing the direction of an electric current


Sorry, no etymologies found.


  • The next steps were to first turn on the petrol, secondly, to switch on the ignition, next to see that the lever to the commutator is retarded as far as possible.

    To Drive a Motorcar | Edwardian Promenade

  • These tubular sections are called the commutator plates.

    Electricity for Boys

  • The mechanical reversal of the current is accomplished by the use of the commutator, which is a metal ring split into halves, well insulated from each other and from the shaft.

    General Science

  • Currents are generated in the coils, now in one direction then in another, as they revolve or cross different parts of the field; and, by means of a device termed a commutator, these currents can be collected or sifted at will, and led away by wires to an electric lamp, an accumulator, or an electric motor, as desired.

    The Story of Electricity

  • But it was easy, by the mechanical arrangement called a commutator, to gather up the currents and cause them to flow in the same direction.

    Fragments of science, V. 1-2

  • The sliders move over a commutator which is a pc board segment.

    Boing Boing

  • This means that spacetime has a commutator structure that is very nonstandard.

    Can a Really, Really Fast Spacecraft Turn Into A Black Hole? | Universe Today

  • Major maintenance items on DC motors were the brushes and commutator wear.

    Bombardier presentation to the Transport Action Group « Stephen Rees's blog

  • Now, if voltages are very high, the resistance at the point where the commutators and the brushes are in contact will create arcs which waste current and are also likely to destroy the commutator.

    Energy and Society~ Chapter 5~ Steam~ Key to the Industrial Revolution

  • Now, I am not sure why Gen Richards is pontificating on matters political The BBC does not ask nor am I clear on why the BBC could not find any commutator who might take issue with this interpretation of future strategy, perhaps you can help?

    Archive 2009-08-08


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