Answer: spectral

AnswerCrossword Clue
SPECTRALGhostly
SPECTRALLike the colors of a rainbow
SPECTRALPhantom
SPECTRALPhantomlike
SPECTRALEerie
SPECTRALGhostly.
SPECTRALSpooky
SPECTRALLike the colors of the rainbow
spectralresembling a specter (a visible disembodied spirit, also SPECTRE)
spectralOf or concerning spectra or the spectrum
spectralOf or like a ghost