A slight degree of difference in anything perceptible; a very slight variation or difference in color or tone.
Throughout these eight or ten volumes he proves himself to be one of those rare writers who see what they write. As in the case of Tennyson, than whom no English poet, in spite of nearsightedness, has observed so minutely the tiniest details of form or the faintest nuance of color, so the lack of normal vision did not prevent Roosevelt from being the closest of observers. He was also, by the way, a good shot with rifle or pistol.
—William Roscoe Thayer Theodore Roosevelt (1919)