Ethiopian calendar (Amharic: የኢትዮጵያ ዘመን አቆጣጠር; yä'Ityoṗṗya zëmän aḳoṭaṭär) or Eritrean calendar - Official calendar in Ethiopia, based on the Coptic calendar with a leap day, every four years. It has twelve months with 30 days each and a thirteenth month called Pagume with five or six days depending on the year.
Epagomenal days
Epagomenal days - An intercalary month of five days (six days in leap years) in ancient Egyptian, Coptic, and Ethiopian calendars.