Definitions of farther:

• adjective:   more distant in especially space or time

  Example: "They live in the farther house"

• adjective:   more distant in especially degree

  Example: "Farther from the truth"

• adverb:   to or at a greater distance in time or space (`farther' is used more frequently than `further' in this physical sense)

  Example: "Farther north"

• adverb:   to or at a greater extent or degree or a more advanced stage (`further' is used more often than `farther' in this abstract sense)

  Example: "The application of the law was extended farther"