"Al-Mulakhkhas fi al-lughat," by Abu al-Fath Hamd ibn Ahmad ibn Hussayn Badi known as Kafi, a learned 12th or 13th Century, Iranian lexicographer and language scholar, is one of the oldest extant Arabic-Persian dictionaries. The dictionary is divided into over twenty chapters, including an alphabetical Arabic-Persian glossary according to Arabic stems as well as lexicons of various types of mathematics, astronomy, calculus, accounting, government administration, land surveying, theology, poetry and prosody, and names of the months and the days of the week in Arabic and Persian. The meticulous editing by Gholamreza Dadkhah and Abbas Goodarznia based on the only available copy of this work provides students and scholars of Persian language, linguistics, and literary studies not only with a rare valuable manuscript but also with a rich source of Persian equivalents of Arabic terms, some of which have lost currency over the centuries as well as others that have been revived in the course of the 20th and 21st centuries. This edition includes an appendix on the rare Persian words and phrases contained in the work.