Ekballō (ἐκβάλλω) is a compound of ek (G1537, out of) + ballō (G906, to throw). It means to throw out, drive out, expel, or send out. It appears about 81 times in the NT and is the standard verb used for Jesus casting out demons (daimonia ekballein).
The word is also used for throwing someone out of a place (John 9:34-35, the man born blind cast out of the synagogue), sending workers into the harvest (Matt. 9:38), and pulling a plank from one's own eye (Matt. 7:4-5).
The exorcisms of Jesus are not merely incidental healings — they are proclamations of the Kingdom. "If it is by the finger of God that I cast out [ekballō] demons, then the kingdom of God has come upon you" (Luke 11:20). Each act of ekballō is a territorial skirmish — the strong man's domain being plundered (Mark 3:27). Jesus enters the enemy's house and expels his occupants.
The authority to ekballō demons was extended to the twelve (Matt. 10:8), to the seventy-two (Luke 10:17), and promised to believers generally (Mark 16:17). This authority derives entirely from the name and power of Jesus — as Acts 19:13-16 dramatically demonstrates when those without genuine union with Christ attempt it and fail. The church continues the Spirit-empowered work of expelling darkness wherever the Kingdom advances.