far
Old English feor "distant; remote; foreign; comparative firra, superlative fyrrest; akin to Old Saxon fer, Old Norse fjarr, Old High German ver, Gothic fairra; all from PIE root per- (1) "to lead, pass over"/ˈfəːðɪst/
The furthest planet from the sun is Neptune.
She had traveled the furthest distance of any of the other runners.
He lived in the furthest reaches of the kingdom.