Al-Qāmus al-Muḥīṭ (Arabic: القاموس المحيط, lit. 'The Encompassing Ōkeanós') is an Arabic dictionary compiled by the lexicographer and linguist, Abū al-Ṭāhir Majīd al-Dīn Muḥammad ibn Ya’qūb ibn Muḥammad ibn Ibrāhīm al-Shīrāzī al-Fīrūzābādī (1329–1414), commonly known as Firuzabadi.^[1][2][3]

Al-Firuzabadi originally intended to produce the largest dictionary, recording the complete language in sixty volumes. However, he ended up writing only two volumes, which nonetheless included a respectable sixty thousand entries. By being incredibly frugal with his definitions and adding a number of abbreviations to his dictionary, such as m (for ma'ruf, "known") to denote words of common usage that required no additional lexicographical description or j (for jam, "plural"), he was able to fit all these entries into such a small space. Modern Arabic dictionaries still use some of these abbreviations. The Qamus became a very popular dictionary for private use, to the point where the Arabic word for "Qamus" which means "Ocean" has become the current word for "dictionary".^[4]

The giant lexicon, Taj al-ʿArus Min Jawahir al-Qamus by Murtada al-Zabidi authored this work as an extension. He completed, revised, and expanded the authoritative Arabic dictionary al-Qamus al-Muhit, in order to compile an Arabic lexicon of such scope and comprehensiveness.^[5]

In recent years, efforts have been made to convert Al-Qāmus al-Muḥīṭ into digital formats, such as the Lexical Markup Framework (LMF), to make it more accessible to modern researchers and scholars.^[6]