'non-spectral' is an English compound formed from the negative prefix 'non-' and the adjective 'spectral.' 'non-' comes from Latin 'non' meaning 'not,' used in English as a productive negative prefix.

'spectral' derives from Latin 'spectrum' (image, apparition) and Late Latin/Old French forms (e.g. 'spectre'), which entered Middle English as 'spectre' and later gave rise to the adjective 'spectral.' The modern compound 'non-spectral' is a straightforward negation formed in English by attaching 'non-' to 'spectral.'

Originally related to 'spectrum' and 'apparition' (image or ghost), 'spectral' came to mean both 'relating to a specter' and 'relating to a spectrum' in scientific contexts. 'Non-spectral' therefore evolved as the simple negation meaning 'not spectral' in either sense.