Jewish calendar a complex ancient calendar in use among Jewish people. It is a lunar calendar adapted to the solar year, normally consisting of twelve months but having thirteen months in leap years, which occur seven times in every cycle of nineteen years. The years are reckoned from the Creation (which is placed at 3761 bc); there are 12 months, with an intercalary month (First Adar) being added in leap years. The religious year begins with Nisan and ends with Adar, while the civil year begins with Tishri and ends with Elul.
Jewish New Year another term for Rosh Hashana.