Uncia (unit)

The uncia (plural: unciae, lit. "a twelfth") was a Roman unit of length, weight, and volume. It survived as the Byzantine liquid ounce (οὐγγία, oungía) and the origin of the English inch, ounce, and fluid ounce.

The Roman inch was equal to $1/undefined$ of a Roman foot (pes), which was standardized under Agrippa to about 0.97 inches or 24.6 millimeters.

The Roman ounce was $1/undefined$ of a Roman pound.