Ismail ibn Hammad al-Jawhari

Abu Nasr Isma'il ibn Hammad al-Jawhari also spelled al-Jauhari (died 1002 or 1008) was the author of a notable Arabic dictionary.

He was born in the city of Farab (Otrar) in Turkestan (in today's southern Kazakhstan). He studied Arabic language first in Baghdad and then among the Arabs of the Hejaz. Then he settled in northern Khorasan (at Damghan and subsequently at Nishapur). He died at Nishapur while attempting flight from the roof of a mosque, possibly inspired by an earlier glider flight by Abbas Ibn Firnas.

His great work is the Arabic dictionary entitled Taj al-Lugha wa Sihah al-Arabiya, "The Crown of Language and the Correct Arabic", also known by the shorter titles al-Sihah fi al-Lugha, "The Correct Language", and al-Sihah. It contains about 40000 dictionary entries. He wrote it when living in Nishapur. It is told that he had not completed it at his death and it was completed by a student. Al-Jawhari put the words into an alphabetical order under which the last letter of a word's root is the first ordering criterion. Al-Sihah is one of the main Arabic dictionaries of the medieval era. Moreover much of its material was incorporated into later Arabic dictionaries compiled by others. A number of abridgements of it, as well as expansions of it, were produced in Arabic over the centuries. A fully searchable online edition is at Baheth.info. Most of it was copied into the huge 13th century dictionary compilation Lisan al-Arab, which is also online at Baheth.info.