The Greek compound adjective ekphobos combines ek (out of, thoroughly) with phobos (fear), meaning "frightened out of one's senses" or "greatly afraid." It appears in Mark 9:6 (the Transfiguration: Peter did not know what to say, "for they were terrified") and in Hebrews 12:21 (Moses said, "I am terrified and trembling" at Sinai).
The word ekphobos (terrified) describes the primal human response to direct encounter with divine glory. At the Transfiguration (Mark 9:6), the disciples were ekphobos — frightened out of their wits. At Sinai (Hebrews 12:21), even Moses was ekphobos before God's manifest presence. This holy terror is not opposed to faith but is part of it — the recognition that we stand before one who is infinitely greater, holy, and powerful. The fear of the LORD is the beginning of wisdom, and ekphobos is where wisdom begins.