Word Origin & History
spook (n.)
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.