The Greek interjection ea is an exclamation of surprise, alarm, or command — roughly equivalent to 'ah!', 'ha!', or 'leave us alone!' It appears in Luke 4:34 in the words of the demonic spirit that cries out when confronted by Jesus in the synagogue at Capernaum.
The demon's cry ea! is the involuntary recognition of a superior power. Confronted with the Holy One of God, the unclean spirit shouts: 'Ha! What do you want with us, Jesus of Nazareth? Have you come to destroy us?' The exclamation reveals the terror of the demonic realm before Christ's authority. This moment is significant: in the synagogue — a place of worship and teaching — an unclean spirit had been present, apparently undetected. Jesus' arrival immediately exposed and expelled it. The gospel regularly disrupts comfortable, religious settings, forcing a confrontation with the real and powerful Christ who tolerates no rivals.