adverb

at or by the greatest distance (used to indicate how far one thing or person is or becomes distant from another).

the bed furthest from the window

adjective

situated at the greatest distance from a specified or understood point.

the furthest door led to a kitchen

most distant,most remote,remotest,furthest/farthest away,farthest,furthermost,farthermost,outlying,outer,outermost,extreme,uttermost,ultimate,very,outmost