Synonyms for Horrify:

n.

astound, shake up, surprise, stun, spring a surprise, astonish, stagger, flash mob, amaze. daunt, fear, shake, consternate. dismay (noun)
daunt.
horrify (noun)
appal, appall, dismay, alarm.
terrify (noun)
study at dismay.

v.

frighten (verb)
harrow, unnerve, rattle, petrify, panic, agitate, set on edge, disturb, terrify, threaten, frighten, alarm, intimidate, scare, haunt.
haunt (verb)
spook.
scare (verb)
daunt, alarm, dismay, petrify, appall, shake, frighten, terrify, intimidate, consternate.

Other synonyms:

consternate. shake. dismay
consternate.
frighten
petrify.
Other relevant words:
daunt, appall, amaze, stun, astound, dismay, astonish, consternate, shake, appal, stagger, surprise, fear.