Answer
This is an official answer by QuranicNames.com Staff
Mahnoor means moonlight in Farsi and Urdu. "Mah" means moon and it is not an Arabic/Islamic word, Noor means "light" and it is a Quranic word and one of the names of Allah (swt) and the name of a Sura in the Quran. Since it contains the word "noor" you can consider it a Quranic name and since the meaning is good inshAllah you can use it.