Judah ben Elijah Hadassi (in Hebrew, Yehuda ben Eliyahu) was a Karaite Jewish scholar, controversialist, and liturgist who flourished at Constantinople in the middle of the twelfth century. He was known by the nickname "ha-Abel," which signifies "mourner of Zion." Neubauer thinks that "Hadassi" means "native of Edessa"[1]
Nothing of Hadassi's life is known except that he was the pupil of his elder brother Nathan Hadassi.
He dealt with Hebrew grammar, Masorah, theology, and philosophy, and knew Arabic and Greek well.[2]