The Romans did not number each day of a month from the first to the last day. Instead, they counted back from three fixed points of the month: the Nones (the 5th or 7th, nine days inclusive before the Ides), the Ides (the 13th for most months, but the 15th in March, May, July, and October), and the Kalends (1st of the following month). Originally the Ides were supposed to be determined by the full moon, reflecting the lunar origin of the Roman calendar. In the earliest calendar, the Ides of March would have been the first full moon of the new year.[3]
Some “ides” connection?
Look for a Roman Era / Latin scholar?