Abū’l-Ḥasan ʻAlī ibn Ismāʻīl (أبو الحسن على بن اسماعيل), known as Ibn Sīdah (ابن سيده), or Ibn Sīdah'l-Mursī (ابن سيده المرسي), (c.1007-1066), was a linguist, philologist and lexicographer of Classical Arabic from Andalusia. He compiled the encyclopedia al-Kitāb al-Mukhaṣṣaṣ (المخصص)(Book of Customs) and the Arabic language dictionary Al-Muḥkam wa-al-muḥīt al-aʻẓam (المحكم والمحيط الأعظم) (The Great and Comprehensive Arbiter". His contributions to the sciences of language, literature and logic were considerable.
Ibn Sīdah was born in Murcia in eastern Andalusia. The historian Khalaf ibn ʻAbd al-Malik Ibn Bashkuwāl (ابن بشكوال) (1183-1101) in his book Kitāb aṣ-Ṣilah (كتاب الصلة) (Book of Relations) gives Ismāʻīl as the name of his father, in agreement with name given in the Mukhassas. However Al-Fath ibn Khaqan in mathmah al-anfus (مطمح الأنفس) has the name Aḥmad. Yaqut al-Hamawi in The Lexicon of Literature, says Ibn Sīdah ('son of a woman') was his nickname. Remarkably both he and his father were blind. His father was a sculptor although it seems the disciplines he devoted his life to, philology and lexicography, had been in his family.
Mohammed bin Ahmed bin Othman Al-Dhahabi's biographic encyclopedia Siyar A'lam al-Nubala (سير أعلام النبلاء) (Lives of The Noble Scholars) is the main biographic source. He lived in the taifa principality of "Dénia and the Eastern Islands" (طائفة دانية والجزائر الشرقية) under the rule of Emir Mujahid al-Amiri al-Muwaffaq (الأمير مجاهد العامري) (1044-1014) and he travelled to Mecca and Medina. He studied in Cordova under the renowned grammarian Abu al-Sa'ad ibn al-Hasan al-Rubai al-Baghdadi (أبو العلاء صاعد بن الحسن الربعي البغدادي) (d.417AH/1026AD) exiled in Andalusia, and with Abu Omar al-Talmanki (أبي عمر الطلمنكي)(429-340AH). He died in Dénia.
- al-Mukhaṣṣaṣ (المخصص) 'Allowance' (20 vols)
- Al-Muḥkam wa-al-muḥīt al-aʻẓam (المحكم والمحيط الأعظم) (Beirut, 2000); Arabic dictionary, 11 vols. A principal source for the famous Lisān al-ʿArab dictionary by the great thirteenth-century lexicographer Ibn Manzur.
- al-Hukam wa'l muhitu'l adhim (المحكم والمحيط الأعظم) 'The Great Comprehensive Reference'
- al-Uniq (الأنيق) 'The Elegant'
- Shar' asla' al-Muntaq (شرح إصلاح المنطق) 'Commentary on the Reform of Logic'
- Shar' ma 'ashkal min sha'r al-Mutanbi (شرح ما أشكل من شعر المتنبي) 'Commentary on Forms of al-Mutanabbi (al-Kindi)'s Poems'
- al-'alam fi'lugha ala al-aj'nas (العلام في اللغة على الأجناس) 'Science of Languages of Nations'
- al-'alam wa'l Muta'lm (العالم والمتعلم) 'Knowledge and the Student'
- al-Wafifi alam 'ahkam al-Quwafi (الوافي في علم أحكام القوافي) 'Science of Rhyme Provision'
- al-'awis fi shar' 'Isla' l-Muntaq (العويص في شرح إصلاح المنطق) 'Sharp Explanation of Logic'
- Shar' Kitab al-'Akhafash (شرح كتاب الأخفش) 'Commentary on Book of the Hidden'
- as-Sma' wa' l-'Alam (السماء والعالم) 'Heaven and Earth'
- al'alam fi'Lughati (العالم في اللغة) 'Philology'
- Shawad al-Lughati (شواذ اللغة) 'Language Lovers'
- Al-Muhkam wal-Muhit al-A'zam (المحكم والمحيط الأعظم) 'The Great and Comprehensive Arbitrator'.