Definition:Roman Weights and Measures/Mass/Uncia
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Definition
The uncia is a unit of mass that was part of the Roman system of weights.
Its value in modern units is estimated to be approximately $423$ grains or $27.4$ grams.
Also see
Historical Note
The uncia continued to be used as a unit of mass in Europe after the fall of Rome, evolving into the ounce.
It is understood to be of the same mass as the apothecaries' ounce and troy ounce, and is about $10 \%$ heavier than the ounce avoirdupois.
Linguistic Note
The word uncia literally means twelfth part, that is: $\dfrac 1 {12}$.
The name derives from the fact that an uncia was $\dfrac 1 {12}$ of a libra.
The plural is unciae.
Sources
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $12$
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $12$