1795-1805, Americanism; < Dutch; cognate with GermanSpuk
When referring to a black person, the term spook dates back to the 1940s. It is used with disparaging intent and is perceived as highly insulting. Black pilots who trained at Tuskegee Institute during World War II were called the Spookwaffe. Some sources say that black pilots reclaimed this derogatory nickname as a self-referential term of pride.
1801, from Du. spook, from M.Du. spooc "spook, ghost," from a common Gmc. source (cf. Ger. Spuk "ghost, apparition," M.L.G. spok "spook," Swed. spok "scarecrow, Norw. spjok "ghost, specter," Dan. spøg "joke"), of unknown origin. Possible outside connections include Lettish spigana "dragon, witch," spiganis "will o' the wisp," Lith. spingu, spingeti "to shine," O.Pruss. spanksti "spark." Meaning "undercover agent" is attested from 1942. The verb is first recorded 1867 in sense of "to walk or act like a ghost;" meaning "to unnerve" is from 1935. The derogatory racial sense of "black person" is attested from 1940s, perhaps from notion of dark skin being difficult to see at night. Black pilots trained at Tuskegee Institute during World War II called themselves the Spookwaffe. Spooky is from 1854.