A line; a letter of the alphabet; an epistle. (1) A figure drawn by exorcists making an incantation. (2) Khatt-i-Sharif, “royal letters; a diploma.” (3) ‘Abdu ‘llah ibn ‘Abbas says a khatt, or “letter,” is the language of the hand, and its divine origin is stated in the Qur’an, Surah xcvi. 4: “Who hath taught us the use of the pen.” It is said Adam first wrote with his finger in the dust, but others say it was Idris. The same traditionist says the first who invented the Arabic character, were three persons of the tribe of Bulan of the race of Banu Taiy.
Ibn Ishaq says there are four classes of Arabic writing : the Makki, and Madani, the Basri, and the Kufi; and the first who wrote the Qur’an in a clear and elegant writing, was Khalid ibn Abi ‘l-Haiyaj, and that he was set to the sork by Sa’d who employed him as a calligraphist for the Khalifah Walid ibn ‘Abdi ‘l-Malik, A.H. 86, and the Khalid wrote it in what is now called the Kufic character. (Khashfu ‘z-Zunun, Flügel’s ed., vol. iii. p. 149.)
Based on Hughes, Dictionary of Islam