Greatly frightened, terrified, completely overcome with fear. Used in Mark 9:6 of the disciples' reaction at the Transfiguration, and in Hebrews 12:21 quoting Moses' terrifying encounter with God at Sinai.
Ekphobos describes the terror of standing in the presence of unveiled divine glory. At the Transfiguration, Peter, James, and John fell to the ground 'terrified' (Mark 9:6). At Sinai, even Moses 'was trembling with fear' (Hebrews 12:21). The author of Hebrews uses this contrast deliberately: the Sinai covenant came with terrifying fire and darkness; the new covenant mountain (Zion) is still awesome but accessible through Jesus' mediating blood (Hebrews 12:22–24). The terror remains — God has not become less holy — but the mediator has changed everything.