ADAR. - The twelfth month, of 29 days (from mid-February to about mid-March), of the Jewish calendar. The name is Babylonian (addaru, in Babylonia the month sacred to the seven great gods [planets]) and appears in the Bible in the post-exilic period (Esd. 6, 15; 11 times in Esth.; 3 times in the two Mach.). In Flavius Josephus its equivalent is the Macedonian Δάστρος. The construction of the second Temple was completed on the 3rd of A. in the 6th year of Darius I (11 March 515 B.C.).
In remembrance of Judas Maccabeus’s victory (161 B.C.) over Nicanor (I Mach. 7, 43, 49; II Mach. 15, 37), « the day of Nicanor » is celebrated on the 13th of A. On the 14th and 15th Purim (v.), still very popular in Judaism today. On the 12th, « the day of Trajan » is celebrated (Ta'anith, 186), although Trajan died on 8 or 9 August (117). On the 7th, the birth and death of Moses are commemorated. From the 15th to the 25th of A., the half-shekel (or didrachm) per head was collected for the Temple (Milānah, Šēgalim, I, 1-III, 1); this is relevant to the chronology of Jesus’ public life (cf. Mt. 17, 23-26).
In order to reconcile the lunar year, which is 11 days shorter, with the solar year, approximately every third year a second adar or we'adar, of 29 days, is added at the end of the Jewish year; it is never mentioned in the Bible.