The OED defines spectrum as "The entire range of wavelengths of electromagnetic radiation, from the longest radio waves to the shortest gamma rays of which the range of visible light is only a small part."
OED definira spektar kao: "Cijeli raspon valnih duljina elektromagnetske radijacije, od najdužih radio valova do najkraćih gama zraka, gdje je raspon vidljivog svijetla samo mali dio."