Mora is the noun form of fear — particularly the awe and reverence that God's mighty acts inspire. It is used both for terrifying dread of enemies and for the reverent fear of YHWH. The word often appears in the phrase 'the fear and awe [mora] of God,' and is linked to the mighty acts of the Exodus — the signs and wonders that struck terror into Egypt and the nations.
The 'fear of the LORD' (yirat Adonai) is a central organizing concept of OT wisdom. Mora adds the dimension of awesome power to this fear — it is not merely polite reverence but the trembling awe that comes from encountering the Holy God. Deuteronomy 11:25 promises that God will put the fear and awe (mora) of Israel upon every land they set foot on. This is not human charisma but divine reputation. The NT equivalent is the early church living in 'the fear of the Lord' (Acts 9:31) — not cowering dread but awesome reverence.