spectral in WordNet English dictionary

1. resembling or characteristic of a phantom
   "a ghostly face at the window"; "a phantasmal presence in the room"; "spectral emanations"; "spiritual tappings at a seance"
   apparitional  ghostlike  ghostly  phantasmal  spectral  spiritual 
   
2. of or relating to a spectrum
   "spectral colors"; "spectral analysis"
   spectral