'Enemy' in the Bible

"When your people Israel are struck down before the enemy, because they have sinned against you; if they turn again to you, and confess your name, and pray and make supplication to you in this house:

"If there is famine in the land, if there is pestilence, if there is blight, mildew, locust or caterpillar; if their enemy besieges them in the land of their cities; whatever plague, whatever sickness there is;

"If your people go out to battle against their enemy, by whatever way you shall send them, and they pray to Yahweh toward the city which you have chosen, and toward the house which I have built for your name;

If they sin against you (for there is no man who doesn't sin), and you are angry with them, and deliver them to the enemy, so that they carry them away captive to the land of the enemy, far off or near;

Ahab said to Elijah, "Have you found me, my enemy?" He answered, "I have found you, because you have sold yourself to do that which is evil in the sight of Yahweh.