瘆 is a stative verb (s.v.) that describes a state of creepy or chilling fear. It is most commonly encountered in the colloquial expression 瘆人 (shèn rén) 'spine-chilling; giving the creeps', often describing a place, atmosphere, or story. You may also hear it in 发瘆 ('to feel a chill of fear') or 瘆得慌 ('to be unnervingly creepy'). This word is more typical of northern Chinese dialects and informal speech.