1854, "frightening;" 1926, "easily frightened," from spook (n. or v.) + -y (2). Related: Spookily; spookiness.
Entries linking to spooky
spook n.
1801, "spectre, apparition, ghost," from Dutch spook, from Middle Dutch spooc "spook, ghost," from a common Germanic source (German Spuk "ghost, apparition," Middle Low German spok "spook," Swedish spok "scarecrow," Norwegian spjok "ghost, specter," Danish spøg "joke"), of unknown origin. According to Klein's sources, possible outside connections include Lettish spigana "dragon, witch," spiganis "will o' the wisp," Lithuanian spingu, spingėti "to shine," Old Prussian spanksti "spark."
Meaning "undercover agent" is attested from 1942. 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.
-y 2
adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.