In the traditional terminology, "ultraviolet" and "infrared" are abbreviations for "ultraviolet light" and "infrared light", so ultraviolet and infrared were definitely always classified as kinds of light.
However, what was initially called "infrared light" is what is called now "near infrared". What is called now "far infrared" was traditionally called "radiant heat", which is a term that dates from before it became understood that both radiant heat and light are electromagnetic waves.
The traditional divisions between radio waves, radiant heat, light and X rays were determined by the fact that each of these 4 required different kinds of emitting and detecting devices. However the evolution of technology has extended the ranges for each kind of emitter and detector, so now the ranges of the corresponding kinds of devices are overlapping, so any precise thresholds in the frequency ranges are only conventional.
However, what was initially called "infrared light" is what is called now "near infrared". What is called now "far infrared" was traditionally called "radiant heat", which is a term that dates from before it became understood that both radiant heat and light are electromagnetic waves.
The traditional divisions between radio waves, radiant heat, light and X rays were determined by the fact that each of these 4 required different kinds of emitting and detecting devices. However the evolution of technology has extended the ranges for each kind of emitter and detector, so now the ranges of the corresponding kinds of devices are overlapping, so any precise thresholds in the frequency ranges are only conventional.