Spooky things make a shiver go down your spine—they're scary or creepy. A movie's spooky music might be enough to make you cover your eyes in fear.
This informal adjective is perfect for talking about things that make you feel afraid or deeply uneasy. Haunted houses are spooky, and the sound of quiet footsteps crunching through the leaves outside your tent at night are spooky too—at least until your brother yells, "Boo!" You can also use spooky to mean "easily spooked," like a nervous horse that jumps at the slightest sound.