Uncia

$$\hbox{1 uncia} \equiv {\textstyle{1\over 12}}.$$

The word uncia was Latin for a unit equal to 1/12 of another unit called the as. The words ``inch'' (1/12 of a foot) and ``ounce'' (originally 1/12 of a pound and still 1/12 of a ``Troy pound,'' now used primarily to weigh precious metals) are derived from the word uncia.

See also Calcus, Half, Quarter, Scruple, Unit Fraction

References

Conway, J. H. and Guy, R. K. The Book of Numbers. New York: Springer-Verlag, p. 4, 1996.