An electrical switch, in a generator or motor, that periodically reverses the direction of an electric current.
A binary map in a given group G, given by [g, h] = ghg⁻¹h⁻¹, where g and h are elements of G, which yields the group's identity if and only if the group operation commutes for g and h.
A binary map in a given ring R, given by [a, b] = ab − ba, where a and b are elements of R, which yields the ring's zero element if and only if the multiplication operation commutes for a and b.
An electrical actuator that allows a relatively small electrical voltage or current to control a larger voltage or current.
A track and field discipline where runners take turns in carrying a baton from start to finish. Most common events are 4x100 meter and 4x400 meter competitions.
A series of vehicles travelling in sequence.
A new set of horses kept along a specific route so that they can replace animals that are tired.
A new set of hounds.
A new set of anything.
To pass on or transfer (information).