Of, or pertaining to, spectres; ghostly. / Of, or pertaining to, spectra; classified according to frequency or wavelength (of light etc)

In a spectral manner; like a ghost. / In terms of a spectrum.

A musical composition practice in which compositional decisions are often informed by the analysis of sound spectra

(uncountable) The quality of being spectral or ghostly. / (countable) Something spectral; a ghost, a spectre.

plural of spectrality

The quality of being spectral or ghostly.

plural of spectral theory

(mathematics) Those theories extending the eigenvalue and eigenvector theory of a single square matrix to a much broader theory of the structure of operators in a variety of mathematical spaces.

(astronomy) an indication of the physical and chemical characteristics of a star based on the spectrum of light that it emits

(astronomy) A classification of stars depending on their spectra and luminosity; usually one of O, B, A, F, G, K, M.