As defined by the catholic encyclopedia Exorcism is (1) the act of driving out, or warding off, demons, or evil spirits, from persons, places, or things, which are believed to be possessed or infested by them, or are liable to become victims or instruments of their malice; (2) the means employed for this purpose, especially the solemn and authoritative adjuration of the demon, in the name of God, or any of the higher power in which he is subject
The word, which is not itself biblical, is derived from exorkizo, which is used in the Septuagint (Genesis 24:3 = cause to swear; III(I) Kings 22:16 = adjure), and in Matthew 26:63, by the high priest to Christ, "I adjure thee by the living God. . ."
the authority of all early writers who refer to the subject at all that in the first centuries not only the clergy, but lay Christians also were able by the power of Christ to deliver demoniacs or energumens, and their success was appealed to by the early Apologists as a strong argument for the Divinity of the Christian religion sometimes in addition to words some symbolic action was employed, such as breathing (insufflatio), or laying of hands on the subject, or making the sign of cross. St. Justin speaks of demons flying from "the touch and breathing of Christians" (II Apol., 6)