Each lunar month in the Hebrew calendar is associated with a sign of the zodiac. Adar is Pisces, the Fish. The keyword for Adar or Pisces is oyev or enemy. Moshe (Moses) was born on Adar 7. He overcame the forces of Amalek, the enemy of the Jewish people, who sought to destroy the whole Israelite nation.
At first glance, it is not at all apparent why the last sign of the zodiac be associated with a word that denotes hostility and hate — however, this is not to be taken as a negative trait of the sign, but refers to its innate strength to overcome and defeat its enemy and then to dispel animosity through joy and happiness. All these qualities associated with Adar are expressed in the story of Purim, celebrated on Adar 15, that recalls the miraculous victory over Haman, the arch-enemy of the Jews, by Esther and Mordechai.