Mahavir is not a “full form” word like an acronym. In Jain tradition, Mahāvīra means “the great वीर / great courageous one” — that is, one who is very brave, fearless, and spiritually victorious.

Simple meaning:

• Maha = great
• Vira = brave / courageous

So, Mahavir = Great Brave One.

In Jain Dharma, Bhagwan Mahavir is also called Vardhaman before Kevalgyan.