(3 syl.). Paintings by the Miniatori, a set of monks noted for painting with minium or red-lead. The first miniatures were the initial letters of rubrics, and as the head of the Virgin or some other saint was usually introduced into these illuminated letters, the word came to express a small likeness. The best miniature-painters have been Holbein, Nicholas Hilliard, Isaac Oliver and his son Peter, Samuel Cooper and his brother Alexander, etc.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894