Etymology From Middle English twelve, from Old English twelf (“twelve”), from Proto-Germanic *twalif, an old compound of *twa- (“two”) and *-lif (“left over”) (i.e., two left over after having already counted to ten), from Proto-Indo-European *leyp- (“leave, remain”). Cognate with Saterland Frisian tweelf, tweelif, tweelich (“twelve”), West Frisian tolve (“twelve”), Dutch twaalf (“twelve”), German Low German twalf, twalv (“twelve”), German zwölf (“twelve”), Danish, Swedish and Norwegian tolv (“twelve”), Icelandic tólf (“twelve”).
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The cardinal number occurring after eleven and before thirteen, represented in Arabic numerals as 12 and in Roman numerals as XII.
There are twelve months in a year.
Hopper points out that duodecads have been prominent in every ancient civilization and cites as examples twelve spokes in the wheel of the Hindu Rta, the twelve gates of hell where Egyptian Ra must spend the twelve hours of night, the twelve tribes of Israel, the twelve labors of Hercules, [...]1972, Eleanor Webster Bulatkin, Structural Arithmetic Metaphor in the Oxford "Roland.", Ohio State University Press, →ISBN, page 10:
Etymology From Middle English twelve, from Old English twelf (“twelve”), from Proto-Germanic *twalif, an old compound of *twa- (“two”) and *-lif (“left over”) (i.e., two left over after having already counted to ten), from Proto-Indo-European *leyp- (“leave, remain”). Cognate with Saterland Frisian tweelf, tweelif, tweelich (“twelve”), West Frisian tolve (“twelve”), Dutch twaalf (“twelve”), German Low German twalf, twalv (“twelve”), German zwölf (“twelve”), Danish, Swedish and Norwegian tolv (“twelve”), Icelandic tólf (“twelve”).
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A group of twelve items.
Fractions would be a little easier if we counted by twelves.
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A twelve-bore gun.
In this way Von Esslin ‘inherited’ two fine hammerless twelves which he used once or twice for duck on the Camargue.1982, Lawrence Durrell, Constance (Avignon Quintet), Faber & Faber, published 2004, page 880:
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LawColloquial A jury (normally composed of twelve persons).
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Slang The police; law enforcement, especially a narcotics officer.