You searched for: “farther
farther, further
farther (FAR thur) (adverb)
Usually a reference to how much space dimension there is or how great a distance is, but it should be used only in connection with a physical or a "linear" distance: That town is farther away than William thought.
further (FUR thur) (adjective)
Not always differentiated from farther, but it should be used in referring to a degree, a quantity, or time in quality or degree: The students had to do further research in their project.

The simple rule is to use farther or farthest only when someone is talking about a measurable distance or space, otherwise use further to indicate greater in quantity, time, and degree.

In order to do further research for their geography class, the students went in search of a region that was farther away from their university town than the next village.