ghostly
scared to death
out of one's skin
soul-shaking
scare the hell out of
do someone a frighten
petrifying
fearing
quakingly
dreadingly
shuddersome
fearsomely
afeared
fraidy
'fraid
aghast
panickily
uglysome
scary
shitting planks
terror
fright
afraidly
frighten
scare someone to death
horrified
affright
put the heart across one
frighten the life out of someone
scare
out of a nightmare
scared shitless
frightsomeness
scared spitless
portentously
shit scared
frightsome
brick it
frightenable
frightfulness
pusillanimousness
spookfest
pusillanimity