spook

The word "spook" originates from Dutch spook (meaning "ghost" or "apparition"), which itself traces back to Middle Dutch spooc. It entered English in the early 19th century, retaining its eerie connotation. Later, it gained colloquial use to describe spies (mid-20th century) and as a verb meaning "to scare" (early 20th century). The word’s evolution reflects its journey from folklore to slang, maintaining a core sense of the unseen or unsettling.