- Isfarāyīnī, Muḥammad ibn Muḥammad, d. 1285. Lubb al-albāb fī ʻilm al-iʻrāb3
- Islamic occultism3
- Italy--Naples3
- Italy--Orvieto3
- Italy--Torri in Val di Pesa3
- Jamʻ al-jawāmiʻ fī al-uṣūl (Subkī, Tāj al-Dīn ʻAbd al-Wahhāb ibn ʻAlī)3
- Jaʻbarī, Ibrāhīm ibn ʻUmar, 1242 or 1243-1331 or 1332. Wāḍiḥah fī tajwīd al-Fātiḥah3
- Jewish calendar3
- Jewish magic3
- Jāmiʻ al-ṣaḥīḥ (Muslim ibn al-Ḥajjāj al-Qushayrī)3
- Kanz al-daqāʼiq (Nasafī, ʻAbd Allāh ibn Aḥmad)3
- Kingdom of God3
- Knowledge, Theory of3
- Land grants3
- Latin drama (Comedy)3
- Latin literature, Medieval and modern3
- Leases3
- Manners and customs3
- Manuscripts, Catalan3
- Manuscripts, Judeo-Arabic3