Meaning of SPECTRUM in English
( n. )
The several colored and other rays of which light is composed, separated by the refraction of a prism or other means, and observed or studied either as spread out on a screen, by direct vision, by photography, or otherwise. See Illust. of Light, and Spectroscope.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012