Sfumato

Another quality which was adopted from Leonardo, and of which the Florentines were especially enamoured, was the ‘sfumato’ system—the imperceptible softening of the transitions in half-tints and shadows.

Source: wiktionary

1960, Helmut Ruhemann, Leonardo's Use of Sfumato, in The British Journal of Aesthetics, Volume 1, British Society of Aesthetics, page 233, The interpretation of ‘sfumato’ is equally wrong. In ‘sfumato’ there is no blurring of the outlines which delineate the contours of figures and there is no blending or diminution of the definition of forms or for that matter any mellowing of colours.

Source: wiktionary

It could be said that sfumato is less exact than line and that its forms are less precisely defined, but with these apparent omissions comes a sense of atmosphere. By casting its shadow over concrete form, sfumato dissolves it.

Source: wiktionary

In baroque painting, sfumato is the blurring of outlines and colors amongst objects, as clouds and mountains, or the sea and the sky. Sfumato allows baroque subjectivity to create the near and the familiar among different intelligibilities, thus making cross-cultural dialogues possible and desirable.

Source: wiktionary