baker's dozen

American  

noun

1. a group of 13; a dozen plus one: from the former practice among bakers and other tradespeople of giving 13 items to the dozen as a safeguard against penalties for short weights and measures.

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baker's dozen British  

noun

1. thirteen

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baker's dozen Cultural  

1. Thirteen; bakers once provided an extra roll with every dozen sold.

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baker's dozen Idioms  

1. Thirteen, as in The new bagel store always gives you a baker's dozen. The origins of this term are disputed. One theory is that in times when bread was sold by weight, bakers who short-weighted their customers were heavily fined, and for safety's sake they would sell thirteen loaves for the price of twelve. Another theory is that dealers purchasing bread from bakers were allowed by law to receive thirteen loaves for the price of twelve, the thirteenth representing their cut of profit. [Late 1500s]

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Etymology

Origin of baker's dozen

First recorded in 1590–1600