To say that a word is used least in the noble Quran then it must be mentioned explicitly just once. Then there are many words satisfying your condition, examples:
- Ramadan / chapter 2
- Al-Saeff (The Summer)/ chapter 106
- Zaid ( A companion name) / chapter 33
- Al-feel ( The elephant) / chapter 105
in surate rehman ayaan word is used in the holy quran
aliph
None !! All the holy Quran is in Arabic.
The word Zikr was mentioned in the holy quran 269 times!
6 word
The Entire Holy Quran is purely Arabic, it has no single non-Arabian word nor a letter.
surah Al-Alaq
word noor in quran 23 later
Tarteel is an Arabic word which has a wide meaning. In Islam the word is used to refer to the proper method of reciting the Quran. The Quran should be recited with a slow rythmic tone (tarteel). All the letters are to be pronounced cleary using the relevant rules of tajweed. Muslim scholars say that this will help the reciter to understand the Quran. The term tarteel is used in Surah Muzammil in the Quran.
Bis mil lah ir rahman irrahim
There is NO "Allahu Akbar" word in Quran
70 times