(physics) The entire range of wavelengths of all known electromagnetic radiations extending from gamma rays, to X-rays through visible light, infrared, to radio waves.

The colours of the rainbow. / (physics) The distribution of colours produced when white light passes through a prism. / (astronomy, physics) The range of frequencies of visible light.

(physics) The distribution of the intensity of particles or radiation emitted in a nuclear process as a function of energy - a unique signature of each process.

(physics) all the lines in the emission or absorption spectrum of hydrogen; each one corresponding to an allowed transition between quantum energy levels

(physics) The portion of the electromagnetic spectrum which is visible to the human eye (red, orange, yellow, green, blue, and violet).

(physics) The portion of the electromagnetic spectrum that is visible to humans. / (physics) an extension of the human-visible spectrum to include near-visible wavelengths, primarily near infrared.

having a wide scope or range of activity

(physics) An absorption or emission spectrum consisting of bands of closely-spaced lines; characteristic of polyatomic molecules.

(physics) A spectrum, typically produced by a luminous gas, that consists of separate lines typical of particular elements

The range of conditions classified as pervasive developmental disorders, generally held to include autistic disorder, Asperger syndrome, and pervasive developmental disorder - not otherwise specified (PDD-NOS). Also includes childhood disintegrative disorder and Rett syndrome.