Spectral means relating to or produced by a spectrum, the distribution of energy emitted by a radiant source
If you describe someone or something as spectral, you mean that they look like a ghost. She is compelling, spectral, fascinating, an unforgettably unique performer. = ghostly
a dark or bright line in an otherwise continuous spectrum caused by the absorption or emission of light, at a single wavelength, by the movement of electrons between energy levels of an atom or molecule
The photocurrent produced by a given level of incident light varies with the wavelength This relation between the photoelectric sensitivity and wavelength is referred to as the spectral response characteristic and is expressed in terms of photosensitivity, quantum efficiency, etc Spectrum: The resolving of overall vibration into amplitude components as a function of frequency Spot Size: The diameter of the circle formed by the cross section of the field of view of an optical instrument at a given distance Stability: The quality of an instrument or sensor to maintain a consistent output when a constant input is applied