Nundinae

The nundinae (/nənˈdɪnaɪ/, /-niː/), sometimes anglicized to nundines, were the market days of the ancient Roman calendar, forming a kind of weekend including, for a certain period, rest from work for the ruling class (patricians).

The nundinal cycle, market week, or 8-day week (Latin: nundinum or internundinum) was the cycle of days preceding and including each nundinae. These were marked on fasti using nundinal letters from A to H. The earliest form of the Roman calendar is sometimes said to have included exactly 38 such cycles, running for 304 days from March to December before an unorganized expanse of about 50 winter days. The lengths of the Republican and Julian calendars, however, were not evenly divisible by 8; under these systems, the nundinae fell on a different letter each year. These letters formed the basis of the later Christian dominical letters.