ozS

Ozs is not a distinct unit or widely recognized proper noun. In practice, it is sometimes used informally as a plural form of the abbreviation oz, which stands for ounce. In formal writing, however, ounces is preferred, and the plural form of the abbreviation is typically avoided or presented as units with numbers (for example, 5 oz) rather than ozs.

There are two primary kinds of ounces relevant to the symbol oz. The avoirdupois ounce, used for most body mass in the United States and many other countries, is defined as 28.349523125 grams. The Troy ounce is used for precious metals and is defined as 31.1034768 grams. When people refer to ounces of weight, they usually mean these mass units, with the context indicating which system is in use.

Fluid ounces are a separate measurement for volume. In the United States, 1 US fluid ounce is 29.573529 milliliters. In the United Kingdom, 1 imperial (UK) fluid ounce is 28.4130625 milliliters. When writing about liquids, the term “fluid ounces” or the abbreviation “fl oz” is used to distinguish volume from weight; pluralization typically follows the same rules as other units, with the full term preferred in formal writing.

Etymology traces the abbreviation oz to the Latin uncia, meaning a twelfth part, which influenced usage in various measurement systems. Ozs, as a string, has no formal independent meaning beyond informal pluralization of oz and should be avoided in technical or scientific contexts in favor of ounces or the explicit unit name.