These words, both as nouns and modifiers, refer to the greatest distance, the most inclusive boundary of something, the point of its greatest extension, or to anything at its most ample or serious. Farthest and furthest are the superlative forms of farther and further . Farthest applies strictly to the greatest distance, whereas furthest can not only apply identically, with no distinction in shading and meaning, but also to many other situations here, both literal and figurative, particularly where the notions of movement or progress are present.

• Which of these cities are the farthest (or furthest ) from us? This line marks the farthest advance of the glacier; behaviour reflecting the furthest departure from the norm.

Outermost is like farthest in referring strictly to distance, but it is even more specific in suggesting the outside of a plane or solid figure: the outermost layer of skin; the outermost periphery of the Roman Empire’s influence; the outermost planet.

Extreme and ultimate are considerably more general than the other words here; each, however, has an occasionally used area of specific reference. Extreme can apply like farthest and outmost : the extreme edge of the desert. When it refers more generally to great amounts, degrees or intensities, it often suggests an unwise, excessive or grave departure from the norm: the extreme left wing of the party; He always went to extremes with his drinking; an extreme illness. But the word can be compared and, hence, may not be as forceful as furthest : the more extreme of the two positions; Which of these extreme factions went furthest in its demands? Ultimate can refer to something that is last in space or either first or last in time: the ultimate island in the archipelago; the modern word’s ultimate form in Indo-European; the mystery isn’t unravelled until the ultimate chapter of the book. More commonly, the word refers to a final outcome: the ultimate results of our foreign policy. At its most general, ultimate functions more vaguely to indicate the most extreme or perfect from of something: the ultimate catastrophe; a hotel that was the ultimate in luxury.

Utmost and uttermost are the most formal of these words and can refer very generally to anything at its greatest, most extreme , or best. Utmost can apply like the last use of ultimate : the utmost in craftsmanship. An added suggestion here, as in its other uses, may be one of the extreme effort required to reach some goal: We will do our utmost to get it delivered on time. Uttermost can seem like an intensification of utmost in some uses: a crisis that will demand our uttermost in time and patience. Often, the word suggests something severe or final: the martyr’s uttermost sacrifice of his life; his uttermost agony. At its most specific, the word, unlike utmost , can also apply more neutrally to distance: the uttermost tip of South America.