GTO Thyristor
A gate turn-off thyristor (GTO) is a special type of thyristor, which is a high-power (e.g. 1200 V AC) semiconductor device. It was invented by General Electric. GTOs, as opposed to normal thyristors, are fully controllable switches which can be turned on and off by their gate lead.
GTO Thyristors are a special kind of Thyristor.