the return to its starting point of the electron beam in a cathode ray tube, as after the completion of a line in a television picture or of a trace in an oscilloscope.
Origin of flyback
First recorded in 1930–35; noun use of verb phrase fly back
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
the fast return of the spot on a cathode-ray tube after completion of each trace
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012