espectro
/esˈpeɡtɾo/ · B2 · noun · m
spectre, ghost
👻 espectro = spectre/spectrum, from Latin spectrum 'appearance' (specere, to look)
Spanish espectro looks almost like English spectre and spectrum, and all share the Latin root specere, 'to look'. A ghost is something seen; a spectrum is the range of light we see. Both senses are one word.