Between visible light and X-rays there is ultraviolet light.
"shorter"
Visible light is made of rays. There are rays with wavelengths that are shorter than visible light and other with longer wavelength.
Longer than some non-visible ... like ultraviolet and X-rays ... and shorter than other non-visible ... like radio and infrared.
The wavelengths for UV light are shorter than for visible light, but much longer than for x-rays or gamma rays.
ultraviolet radiation and infrared radiation
The color red, whether in an apple or anywhere else, corresponds to a certain range of wavelengths of light, which are the longer wavelengths of the visible spectrum. Blue is composed of the shorter wavelengths.
Infrared light, microwaves and radio waves have wavelengths longer than visible light. Radio waves have the longest wavelength.
Sound waves are much longer then light waves.
The wavelengths of visible light are longer than ultraviolet wavelengths.
Light energy with wavelengths longer than visible red is infrared light.
Radio telescopes and infra-red telescopes operate at longer wavelengths/lower frequencies than visible light. Ultraviolet telescopes operate at shorter wavelengths/higher frequencies than visible light.
UV (ultraviolet) radiation, with wavelengths shorter than visible light, is not heat. IV (intravenous) medication is usually administered at room temperature. IR (infrared) radiation, with wavelengths longer than visible light, is heat.