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1. Someone unpleasantly strange or eccentric
   - creep, weirdo, weirdie, weirdy
    
2. A mental representation of some haunting experience
   "he looked like he had seen a spook"
   - ghost, shade, wraith, specter [US], spectre [Brit, Cdn]
    
3. A person secretly employed in espionage for a government
   - secret agent, intelligence officer, intelligence agent, operative, spy

1. Frighten or scare, and often provoke into a violent action
   "The noise spooked the horse"

Derived forms: spooks, spooking, spooked

Type of: affright, agent, apparition, disagreeable person, fantasm, fright, frighten, phantasm, phantasma, phantom, scare, shadow, unpleasant person

Encyclopedia: Spook