WordWeb Online

1. Inspiring a feeling of fear; strange and frightening
   "an uncomfortable and spooky stillness in the woods";
   - eerie, eery
    
2. Suggestive of the supernatural; mysterious
   "a spooky feeling of déjà vu";
   - eerie
    
3. [N. Amer] Unpredictably excitable (especially of horses)
   - skittish, flighty, nervous, skittery

Derived forms: spookiest, spookier

See also: excitable, strange, supernatural, unusual

Encyclopedia: Spooky