Noah Webster's Dictionary 1. (a.) Scary, alarming, appalling. 2. (a.) Full of that which causes fright; exciting alarm; impressing terror; shocking; as, a frightful chasm, or tempest; a frightful appearance.

Multi-Version Concordance Frightful (2 Occurrences) Job 30:6 So that they dwell in frightful valleys, and in holes of the earth and of the rocks. (WEB ASV YLT) Jeremiah 50:38 a drought is upon her waters, and they shall be dried up; for it is a land of graven images, and they are mad after frightful idols. (DBY)