Frontier

Frontier: The boundaries of a country usually marked out by lines of posts. A frontier is a line either natural or artificial, dividing two states. This line may be straight or may contain a salient bend, a re-entrant bend, or a double re-entrant with salient between. In the case of a straight frontier neither country possesses any advantage. In the case of a frontier with a salient bend the side possessing it may be said to be on the offensive.