n (context|meteorology) The interface or transition zone between two airmasses of different density, often resulting in precipitation. Since the temperature distribution is the most important regulator of atmospheric density, a front almost invariably separates airmasses of different temperature.
n (context|military) An area where army|armies are engaged in conflict, especially the line of contact.
n (context|military) The lateral space occupied by an element measured from the extremity of one flank to the extremity of the other flank.
n (context|military) When a combat situation does not exist or is not assumed, the direction toward which the command is faced.