causing fear or anxiety by threatening great harm; "a dangerous operation"; "a grave situation"; "a grave illness"; "grievous bodily harm"; "a serious wound"; "a serious turn of events"; "a severe case of pneumonia"
2
terrific
causing extreme terror; "a terrifying wail"
2
atrocious
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"