noun
: the minute change in wavelength and marked change in character of many spectral lines in light emanating from the central region of a metallic arc as compared with light originating near the electrodes
noun
: the minute change in wavelength and marked change in character of many spectral lines in light emanating from the central region of a metallic arc as compared with light originating near the electrodes
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012