The definition of a cathode-ray tube (CRT) is a vacuum tube that creates an image on a fluorescent screen when struck by an electromagnetically charged beam.
An example of a cathode-ray tube is what televisions and computers used to create images before LED and LCD were introduced.
a vacuum tube in which a stream of electrons is electromagnetically focused on a fluorescent screen, producing lighted dots: such tubes are used as oscilloscopes and picture tubes: abbrev. CRT
A vacuum tube, used in monitors and televisions, in which a hot cathode emits electrons that are accelerated as a beam through a relatively high voltage anode, further focused or deflected electrostatically or electromagnetically, and allowed to fall on a phosphorescent screen.
(plural cathode ray tubes)