Hamantash is also spelled hamentasch, homentash, homentasch, homentaschan, or even (h)umentash. The name hamantash is commonly viewed as a reference to Haman, the villain of Purim, as described in the Book of Esther. The pastries are supposed to symbolize the defeated enemy of the Jewish people. The word tasche means "pouch" or "pocket" in German, and thus may refer to Haman's pockets, symbolizing the money that Haman offered to Ahasuerus in exchange for permission to destroy the Jews. In Hebrew, tash means "weaken", and the hamantash may celebrate the weakening of Haman and the hope that God will weaken all of the enemies of the Jews. Another possible source of the name is a folk etymology: the Yiddish word מאָן־טאַשן (montashn) for a traditional delicacy, corresponding to the German word Mohntaschen, the plural of Mohntasche, literally meaning "poppyseed pouch", was transformed to hamantaschen, likely by association with Haman. In Israel, hamantaschen are called oznei Haman (Hebrew: אוזני המן), Hebrew for "Haman's ears" in reference to their defeated enemy's ears.
The word "hamantash" is singular; "hamantashen" is plural and is the more common word form. However, many people refer to these pastries as hamantashen even in the singular (for example, "I ate a poppy seed hamantashen"). 
Leave it to the Jews to have a cookie inspired by cultural annihilation! Hamantaschen are the triangular pastries associated with the holiday of Purim , when Jews read from the Book of Esther, the Megillah , and celebrate the triumph of good (Esther) over evil (Haman, who planned to destroy the Jewish people).