Where does “spook” come from?

Spook comes from Dutch spook, from Middle Dutch spooc and spoke, from Proto-Germanic spōk, a word of uncertain origin and meaning.

spook (English): A ghost or phantom; A hobgoblin; A scare or...

Definitions

Step	Language	Word	Meaning
1	Dutch	spook	phantom, ghost; horror, terror; an annoying and...
2	Middle Dutch	spooc	apparition, ghost; spook, ghost
3	Middle Dutch	spoke	—
4	Proto-Germanic	spōk	spook, ghost, apparition; witchcraft, wizardry

spook — Etymology, Origin & Word History | Etymology Explorer