Other forms: terrifyingly
If something is terrifying, it makes you feel extremely afraid. Even if your little sister loves the scary roller coaster at the amusement park, you might still find it terrifying.
Some people feel mildly alarmed when they see a small spider — if you have a phobia about spiders, discovering one in your bathtub is truly terrifying. This alarming adjective comes from the Latin root terrificus ("causing terror"), which it shares with terrific, a word whose meaning was originally just as scary.