The term 'spooky sound' can be represented by four different crossword solutions: CREAK (5 letters), MOAN (4 letters), BOO (3 letters), and ooo (3 letters). Creaking is a sound that is often associated with horror movies, as it is the sound of a door slowly opening or closing. Moaning is a low, drawn-out sound that is often used to represent a ghostly presence. Booing is a sound that is usually made to scare someone, and ooo is a sound that is often used to express surprise or fear. All of these sounds are commonly used to create a spooky atmosphere.