Ounce
Middle English: from Old French unce, from Latin uncia ‘twelfth part (of a pound or foot)’; compare with inch1.
wiktionary
From Middle English ounce, unce, from Middle French once, from Latin uncia(“twelfth part”), from ūnus(“one”). Doublet of inch, uncia, oka, and ouguiya.
From Middle French once, from Old French lonce(“lynx”), by false division (the l was thought to be the article), from Italian lonza, ultimately from Ancient Greek λύγξ(lúnx, “lynx”). Doublet of onza.
etymonline
ounce (n.1)
unit of weight, the twelfth part of a pound, early 14c., from Old French once, unce, a measure of weight or time (12c.), from Latin uncia "one-twelfth part" (of a pound, a foot, etc.), from Latin unus "one" (from PIE root *oi-no- "one, unique"). The Latin word had been adopted in Old English as ynce (see inch).
It was one-twelfth of a pound in the Troy system of weights, but one-sixteenth in avoirdupois. Abbreviation oz. is from older Italian onza. It was used loosely from late 14c. for "a small quantity." Also used in Middle English as a measure of time (7.5 seconds) and length (about 3 inches). In figurative expressions and proverbs, an ounce of X is compared or contrasted with a pound of Y from 1520s.
ounce (n.2)
"wildcat," c. 1300, from Old French once "lynx" (13c.), from lonce, with l- mistaken as definite article, from Vulgar Latin *luncea, from Latin lyncea "lynx-like," from lynx (see lynx). Originally the common lynx, later extended to other large, spotted wildcats, now mainly used of the mountain-panther or snow leopard of Asia.
