terrifying
After four chemotherapy treatments, the cancer that had grown so terrifyingly fast in the spring was now no longer detectable.
This is a plot that deepens as surprises explode unexpectedly and terrifyingly.
It skidded terrifyingly along the runway amid clouds of dust.
He was responsible for some of America's most terrifyingly violent crimes.
Last night I dreamed terrifyingly about witchdoctors and ghosts.

SMART Vocabulary: related words and phrases

Describing things that cause fear
awesome
awesomely
awesomeness
bloodcurdling
chilling
fearsome
fearsomely
frightening
frighteningly
greasily
imposingly
intimidating
intimidatingly
scarifying
scarifyingly
spookily
spooky
terrifying
traumatic
traumatically