ounceyoudaoicibaDictYouDict[ounce 词源字典]
ounce: English has two separate words ounce. The ‘measure of weight’ [14] is etymologically the same word as inch. It comes from the same ultimate source, Latin uncia ‘twelfth part’, but whereas inch reached English via prehistoric Germanic, ounce’s route was through Old French unce. Its original use was in the Troy system of weights, where it still denotes ‘one twelfth of a pound’, but in the avoirdupois system it came to be applied to ‘one sixteenth of a pound’.

Its abbreviation, oz [16], comes from Italian onza. Ounce [13] ‘big cat’ comes from the same source as lynx (and indeed it originally meant ‘lynx’; ‘snow leopard’ is an 18th-century reapplication of the name). It represents an alteration of Old French lonce, based on the misapprehension that the initial l represented the definite article.

This in turn came via Vulgar Latin *luncia from Latin lynx, source of English lynx.
=> inch, one; light, lynx[ounce etymology, ounce origin, 英语词源]
ounce (n.1)youdaoicibaDictYouDict
unit of weight, early 14c., from Old French once, unce, a measure of weight or time (12c.), from Latin uncia "one-twelfth part" (of a pound, foot, etc.), from Latin unus "one" (see one). 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. Also used in Middle English as a measure of time (7.5 seconds) and length (about 3 inches).
ounce (n.2)youdaoicibaDictYouDict
"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 wildcats, now mainly used of the mountain-panther or snow leopard of Asia.