frightful

adjectives

provoking horror
"an atrocious automobile accident"; "a frightful crime of decapitation"; "an alarming, even horrifying, picture"; "war is beyond all words horrible"- Winston Churchill; "an ugly wound"
atrocious, frightful, horrible, horrifying, ugly
is derived from
frightfulness
extreme in degree or extent or amount or impact
"in a frightful hurry"; "spent a frightful amount of money"
awful, frightful, terrible, tremendous
extremely distressing
"fearful slum conditions"; "a frightful mistake"
fearful, frightful
is derived from
frightfulness