thyristor (?a??r?st?) n (Electronics) any of a group of semiconductor devices, such as the silicon-controlled rectifier, that can be switched between two states[C20: from thyr(atron) + (trans)istor]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014