To switch or transfer current from one path to another, typically to maintain a constant direction of torque in a rotating machine or to convert alternating current to direct current. In mechanical systems, this is done using brushes and a rotating commutator. In power electronics, solid-state switches like thyristors commutate the current by turning on and off in a precise sequence.
Heard on the job
The thyristor will naturally commutate when the AC voltage waveform crosses zero.