furthest(s = adj.all)farthermost, farthest, furthermost, utmost, uttermost - (comparatives of `far') most remote in space or time or order; "don't go beyond the farthermost (or furthermost) tree"; "explored the furthest reaches of space"; "had traveled to the farthest frontier"; "the utmost tip of the peninsula"
Adverbial has 2 senses
furthest(r = adv.all)farthest - to the greatest degree or extent or most advanced stage (`furthest' is used more often than `farthest' in this abstract sense); "furthest removed from reality"; "she goes farthest in helping us"; "went the furthest of all the children in her education"
furthest(r = adv.all)farthest - to the greatest distance in space or time (`farthest' is used more often than `furthest' in this physical sense); "chose the farthest seat from the door"; "he swam the furthest"; "see who could jump the farthest"
at the height, at the limit, extreme, far out, farthermost, farthest, farthest off, furthermost, greatest, most, most distant, outermost, outmost, radical, remotest, too much, ultimate, ultra, ultra-ultra, utmost, uttermost, way out