uncia

The term "uncia" originates from Latin and signifies "a twelfth part". This unit was fundamental in ancient Roman systems of weights and measures.12

In terms of length, the uncia was equivalent to the modern inch, representing the 12th part of a Roman foot. This Roman foot, or pes, is estimated to be approximately 296 mm or 11.65 inches.23

In Roman weight systems, the uncia also denoted the 12th part of a pound. The Roman pound, or libra, was divided into 12 unciae. This system influenced later units, such as the English ounce, which also represents the 12th part of a troy pound. The uncia also referred to ancient Roman and Sicilian coins, each valued at 1/12 of a larger unit.231