Adar

Adar (Hebrew: אֲדָר‎, Adar ʾĂḏār ; from Akkadian adaru) is the sixth month of the civil year and the twelfth month of the ecclesiastical year on the Hebrew calendar. It is a winter month of 29 days. In leap years, it is preceded by a 30-day intercalary month named Adar Aleph (Aleph being the first letter of the Hebrew alphabet), Adar Rishon (First Adar) or Adar I and it is then itself called Adar Bet (Bet being the second letter of the Hebrew Alphabet), Adar Sheni (Second Adar) or Adar II. Occasionally instead of Adar I and Adar II, "Adar" and "Ve'Adar" are used (Ve means 'and' thus: And Adar). Adar I and II occur during February–March on the Gregorian calendar.

Based on a line in the Mishnah declaring that Purim must be celebrated in Adar II in a leap year (Megillah 1:4), Adar I is considered the "extra" month. As a result, someone born in Adar during a non leap year would celebrate his birthday in Adar II during a leap year. However, someone born during either Adar in a leap year will celebrate his birthday during Adar in a non-leap year, except that someone born on 30 Adar I will celebrate his birthday on 1 Adar in a non-leap year because Adar in a non-leap year has only 29 days, and 30 Adar I is Rosh Chodesh, so his birthday will still fall on Rosh Chodesh Adar.