Dozen
A dozen is a grouping of twelve.
The dozen may be one of the earliest primitive integer groupings, perhaps because there are approximately a dozen cycles of the Moon, or months, in a cycle of the Sun, or year. Twelve is convenient because it has a maximal number of divisors among the numbers up to its double, a property only true of 1, 2, 6, 12, 60, 360, and 2520.
The use of twelve as a base number, known as the duodecimal system, originated in Mesopotamia. Twelve dozen are known as a gross; and twelve gross are called a great gross, a term most often used when shipping or buying items in bulk. A great hundred, also known as a small gross, is 120 or ten dozen.
Dozen may also be used to express a moderately large quantity as in "several dozen".
Varying by country, some products are packaged or sold by the dozen, often foodstuff.
Etymology
The English word dozen comes from the old form douzaine, a French word meaning . This French word is a derivation from the cardinal numeral douze and the collective suffix -aine, a suffix also used to form other words with similar meanings such as quinzaine, vingtaine, centaine, etc. These French words have synonymous cognates in Spanish: docena, quincena, veintena, centena, etc. English dozen, French douzaine, Catalan dotzena, Portuguese "dúzia", Persian dowjin "دوجین", Arabic درزن, Turkish "düzine", Hindi darjan "दर्जन", German Dutzend, Dutch dozijn, Italian dozzina and Polish tuzin, are also used as indefinite quantifiers to mean or .A confusion may arise with the Anglo-Norman dizeyne a tithing, or group of ten households — dating from the earlier English system of grouping households into tens and hundreds for the purposes of law, order and mutual surety. In some texts this 'dizeyne' may be rendered as 'dozen'.
Half a dozen
The phrase "half a dozen" means six of something, as 6 is half of 12. The idiom "six of one, half a dozen of the other" means two options are of equal worth so choosing one is the same as choosing the other.Baker's dozen
A baker's dozen, devil's dozen, or long dozen is 13, one more than a standard dozen. The broadest use of baker's dozen is simply a group of thirteen objects.In medieval England the Assize of Bread and Ale law imposed severe punishments for short measure. Bakers in contravention could be penalized with a fine, a flogging, or destruction of their oven, so avoided the risk of penalty by including an extra unit to be sure the minimum weight was met. The thirteenth piece of bread is called the vantage loaf.
According to the Oxford English Dictionary, the term "baker's dozen" originated in the late 16th century and is "apparently so called after the former practice among bakers of including a thirteenth loaf when selling a dozen to a retailer, the extra loaf representing the retailer's profit."
According to the 1811 Classical Dictionary of the Vulgar Tongue, by Francis Grose, "a Baker's Dozen is Thirteen; that number of rolls being allowed to the purchaser of a dozen". Contrary to most sources, according to the 1785 version of that dictionary, "a Baker's Dozen is Fourteen, that number of rolls being allowed to the purchaser of a dozen".
A lesser-used regionalism is the Texas dozen, which generally consists of 15. This is typically used only in Texas and surrounding areas for such goods as flowers or baked goods, although can be applied to anything that is counted, such as photographs.