What is the meaning of root word nun?

The word "nun" doesn't have a root word in the typical sense. It's a word in its own right, derived from the Latin word "nonna" meaning "aunt" or "old woman".

The connection to the modern word "nun" comes from the fact that early Christian communities often had women who lived a life of service and devotion, and were often referred to as "aunt" or "elder woman" by the community.

So, while "nun" doesn't have a simple root word, its origin is connected to the Latin word "nonna" and the societal roles of women in early Christianity.