Ornamentation is simply any form of decoration on a piece of architecture. Ornamentation is often embedded in structures, windows, or other pieces of architecture. In some styles, it is difficult to distinguish what is ornamentation and what is pure function.

An oculus is a circular opening at the center of a dome. One of the most popular examples of an oculus is in the Pantheon.
If you want to learn more about the Pantheon, be sure to read our article: 9 Facts About the Pantheon, the Iconic Roman Church That Barely Survived the Dark Ages

Words or short lines at the beginning or end of a paragraph, isolated from the main content.

The degree of a color’s transparency, influencing the visibility of underlying elements.