Satan - (Easton's Bible Dictionary)
Adversary; accuser. When used as a proper name, the Hebrew word so rendered has the article "the adversary" (Job 1:6-12; 2:1-7). In the New Testament it is used as interchangeable with Diabolos, or the devil, and is so used more than thirty times.
He is also called "the dragon," "the old serpent" (Rev. 12:9; 20:2); "the prince of this world" (John 12:31; 14:30); "the prince of the power of the air" (Eph. 2:2); "the god of this world" (2 Cor. 4:4); "the spirit that now worketh in the children of disobedience" (Eph. 2:2). The distinct personality of Satan and his activity among men are thus obviously recognized. He tempted our Lord in the wilderness (Matt. 4:1-11). He is "Beelzebub, the prince of the devils" (12:24). He is "the constant enemy of God, of Christ, of the divine kingdom, of the followers of Christ, and of all truth; full of falsehood and all malice, and exciting and seducing to evil in every possible way." His power is very great in the world. He is a "roaring lion, seeking whom he may devour" (1 Pet. 5:8). Men are said to be "taken captive by him" (2 Tim. 2:26). Christians are warned against his "devices" (2 Cor. 2:11), and called on to "resist" him (James 4:7). Christ redeems his people from "him that had the power of death, that is, the devil" (Heb. 2:14). Satan has the "power of death," not as lord, but simply as executioner.