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:''This article is about the unit of mass. For the unit of volume, see Fluid ounce. For all other uses, see Ounce (disambiguation).'' An ounce (abbreviated oz; apothecary symbol: ℥) is a unit of mass used in some systems of measurement. Whilst various definitions have been used throughout history, two remain in common use: the avoirdupois ounce equal to approximately 28.3 g and the troy ounce of about 31.1 g. The avoirdupois ounce is widely used as part of the United States customary and British imperial systems, but the troy ounce is now only commonly used for the mass of precious metals such as gold. == Etymology == ''Ounce'' derives from Latin ''uncia'', a unit that was one twelfth () of the Roman pound (''libra''). ''Ounce'' was borrowed twice: first into Old English as ''ynsan'' or ''yndsan'' from an unattested Vulgar Latin form with ''ts'' for ''c'' before ''i'' (palatalization) and second into Middle English through Anglo-Norman and Middle French (''unce'', ''once'', ''ounce''). The abbreviation ''oz'' came later from the cognate Italian word (now spelled ). ''Inch'' comes from the same Latin word, but differs because it was borrowed into Old English and underwent i-mutation or umlaut (''u'' → ''y'') and palatalization (''k'' → ''ch''). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ounce」の詳細全文を読む スポンサード リンク
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