spook

informalA ghost or phantom.

“The building was haunted by a couple of spooks.”

A hobgoblin.

informalA scare or fright.

“The big spider gave me a spook.”

espionageslangAn undercover agent or spy.

philosophyA metaphysical manifestation; an artificial distinction or construct.

USslangmedicineA psychiatrist.

blackjackslangA player who engages in hole carding by attempting to glimpse the dealer's hole card when the dealer checks under an ace or a 10 to see if a blackjack is present.

Someone unpleasantly strange or eccentricperson

A mental representation of some haunting experience

“he looked like he had seen a ghost”

“it aroused specters from his past”

To frighten or make nervous (especially by startling).

“The hunters were spooked when the black cat crossed their path. The movement in the bushes spooked the deer and they ran.”

To become frightened (by something startling).

“The deer spooked at the sound of the dogs.”

To haunt.

Frighten or scare, and often provoke into a violent action

“The noise spooked the horse”