Which is the correct word, Ramadan or Ramzan?

The word Ramadhan ( رَمَضان ) has its origin in Arabic language, its name of a Lunar month among 12 months of Islamic Year. As Islam has its own Islamic Calender which is based on moon sighting afte every 29 or 30 days. This calendar is also known as Hijri calendar.

Arabic is an official language of Islam and the holy book named The Quran was revealed in Arabic language.   As muslims moved from Arab origin to east sides, the language also travelled. In India-Pakistan ( almost subcontinent) Arabic language gave birth to another language called Urdu which has more than 80% vocab from Arabic Language.   With Arabic, there are strict rules when reciting(reading) Quran. There are same rules in Urdu language as well but are not followed usually. With time, there are changes to the way letters were pronounced, and many letters end up with same pronounciation although written totally differently.