to or at a greater extent or degree or a more advanced stage (`further' is used more often than `farther' in this abstract sense)
more distant in especially degree
to or at a greater distance in time or space (`farther' is used more frequently than `further' in this physical sense)
more distant in especially space or time
having a common boundary or edge; abutting; touching
nearest in space or position; immediately adjoining without intervening space
near or close to but not necessarily touching
