For generations, Rosh HaShanah, the New Year festival, and Yom Kippur, the Day of Atonement, have been called the Days of Awe
The word “awe” is used here, as in numerous places in the Bible, to express a sense of the sublime, which generates feelings of reverence for God’s majesty.
Our Patriarch Jacob, in describing the place where he had his vision of the ladder to Heaven, says, “How awesome is this place! This is none other than the house of God, and this is the gate of Heaven” (Genesis 28:17).
The word is also mentioned in the Writings, “God is of awesome majesty” (Job 37:22), and in the Song of the Sea, after the miraculous parting of the Red Sea:
“Who is like unto You … awesome in praises, doing wonders?” (Exodus 15:11).
–Rabbi Adin Steinsaltz