bloodcurdling
ˈblʌdkəːdlɪŋ
adjective
causing or expressing terror or horror.
a blood-curdling scream
terrifying,frightening,spine-chilling,hair-raising,chilling,horrifying,petrifying,alarming,shocking,scaring,eerie,sinister,fearsome,horrific,horrible,horrendous,fearful,appalling,eldritch,spooky,scary,creepy