Still"ness (?), n. 1. The quality or state of being still; quietness; silence; calmness; inactivity.

Painting, then, was the art demanded by the modern intellect upon its emergence from the stillness of the Middle Ages.
J. A. Symonds.

2. Habitual silence or quiet; taciturnity.

The gravity and stillness of your youth
The world hath noted.