Ali ibn Mohammed al-Jurjani (1339–1414) (Persian علی بن محمد جرجانی) was a Persian[4] encyclopedic writer, scientist, and traditionalist theologian.

He is referred to as "al-Sayyid al-Sharif" in sources due to his alleged descent from Ali ibn Abi Taleb.

[1] He was born in the village of Ṭāḡu near Astarabad in Gorgan (hence the nisba "Jurjani"),[1] and became a professor in Shiraz.

When this city was plundered by Timur in 1387, he moved to Samarkand, but returned to Shiraz in 1405, and remained there until his death.

[5] The author of more than fifty books,[6] of his thirty-one extant works, many being commentaries on other works, one of the best known is the Taʿrīfāt (تعريفات "Definitions"),[7] which was edited by G Flügel (Leipzig, 1845), published also in Constantinople (1837), Cairo (1866, etc.