Uncia

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.

REFERENCES:

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

Wells, D. The Penguin Dictionary of Curious and Interesting Numbers. New York: Penguin Books, p. 85, 1986.