Fahreddin-i Acemi or Fahreddin Acemî or Molla Fakhr al-Dīn al-‘Ajamī[1] was a 15th-century Ottoman Islamic scholar and Shaykh al-Islam.
[2] He studied, possibly under Seyyid Şerif, in an Acem or Ajam land (a Persian-speaking country), thus his nisba Acemî or ‘Ajamī.
[4] As mufti, Fahreddin is said to have played an important role in reducing Hurufi influence in the Ottoman Empire.
Fahreddin hid himself in a place where the Hurufi and his followers would be speaking--either the sultan's palace or Mahmud Paşa's house--so that he could hear for himself their ideas.
After listening, Fahreddin came out of hiding, told them their errors, and then condemned them harshly in the presence of the sultan.