Mufradaat Alfazul Quran

Al-Mufradat fi Gharib al-Quran: Arabic 
By Imam, Abi al-Qasim al-Husayn bin Muhammad al-Raghib al-Asfahani
Checked and Revision By Haitham Tua'ima
A comprehensive list of rare words used in the Quran and their definitions and usage in Arabic, also one of the earliest dictionary written about the problematic words of the Qur'an. Indexed in alphabetical order.