the series of colours ranging from red, having the longest wavelength, to violet, with the shortest wavelength, that is produced when a beam of white light is dispersed, e.g. by a prism

the components of a beam of electromagnetic radiation arranged in the order of their wavelengths

the entire range of wavelengths or frequencies of electromagnetic radiation or of any particular type of it

a series of images formed when a beam of a particular type of electromagnetic radiation, e.g. X-rays, ultraviolet radiation, or radio waves, is dispersed and then brought to a focus so that the components of the beam are arranged in the order of their wavelengths

= electromagnetic spectrum

the range of frequencies of sound waves

an interrelated sequence or range

a wide spectrum of interests