- Istiṣḥāb (Islamic law)3
- Italy--Sicily3
- Iʻrāb ʻan qawāʻid al-iʻrāb (Ibn Hishām, ʻAbd Allāh ibn Yūsuf)3
- Iṣfahānī, Maḥmūd ibn ʻAbd al-Raḥmān, 1275 or 1276-1348 or 1349. Tashyīd al-Qawāʻid3
- James, the Greater, Saint3
- Jamʻ al-jawāmiʻ fī al-uṣūl (Subkī, Tāj al-Dīn ʻAbd al-Wahhāb ibn ʻAlī)3
- Jaʻbarī, Arslān ibn Yaʻqūb, -1300. Risālat al-tawḥīd3
- Jerome, Saint, -419 or 4203
- Jews--Medicine3
- Judaism--Prayers and devotions3
- Jurjānī, ʻAlī ibn Muḥammad, al-Sayyid al-Sharīf, 1340-1413. Ḥāshiyah ʻalá Sharḥ Shamsīyah3
- Khalwatīyah3
- Khiḍr (Legendary character)3
- Knowledge, Theory of (Islam)3
- Kāfī (Kulaynī, Muḥammad ibn Yaʻqūb)3
- Latin language--Grammar3
- Latin poetry, Medieval and modern3
- Laylat al-Qadr3
- Letter writing3
- Loans (Islamic law)3