Al-Khalil ibn Ahmad al-Farahidi

Al-Khalil ibn Ahmad al-Farahidi (c. 100–170 AH / c. 718–786 CE) was one of the founding figures of the Arabic linguistic sciences. He worked in Basra, in southern Iraq, then a leading center of learning, where he taught and composed his major works. He is traditionally said to have been of the Azd tribe and of Omani origin, his nisba "al-Farahidi" tracing to an ancestor; some early reports instead place his birth in Basra or (per the grammarian al-Sirafi) Siraf, so his exact birthplace is not settled.

He is credited with two landmark achievements. The first is Kitab al-Ayn ("The Book of [the letter] Ayn"), regarded as the first comprehensive Arabic dictionary, which arranged words by the point of articulation of their sounds rather than alphabetically. The second is the founding of arud, the systematic science of Arabic poetic meter. His most famous student was Sibawayh, author of the foundational grammar known as al-Kitab; he also taught al-Asma'i and al-Nadr ibn Shumail.

Sources describe him as living simply and piously, in a small reed house, and report that he made the pilgrimage to Mecca; these portraits come from later biographical tradition. His sectarian affiliation is disputed: some accounts class him as Sunni, while much Omani and Ibadi tradition holds that he was a companion of the early Ibadi figure Jabir ibn Zayd and died an Ibadi. He is said to have died at Basra, by tradition after an accident.