noun The foremost side of something or the end that faces the direction it normally moves.
noun The side of a building with the main entrance.
I'll go out the front, and you go out the back.
noun A field of activity.
noun A person or institution acting as the public face of some other, covert group.
Officially it's a dry-cleaning shop, but everyone knows it's a front for the mafia.
noun 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.
We need to take the clothes off the line. The news reported a front is coming in from the east, and we can expect heavy rain and maybe hail.
noun An area where armies are engaged in conflict, especially the line of contact.
noun The lateral space occupied by an element measured from the extremity of one flank to the extremity of the other flank.