In Jainism, the word “Jina” has a very clear and special meaning:

• Literal meaning:

“Jina” = Conqueror / Victor.

• What is conquered?

Not other people, but one’s own inner enemies: - anger (krodh) - pride (maan) - deceit (maya) - greed (lobh) and all attachment–aversion (raag–dvesh) and delusion (mithyātva). ( jainknowledge.com)

• Who is called Jina?

A Tirthankara / Arihant who has: - completely destroyed these inner passions - attained Keval Jnana (omniscience) - shown the path of liberation (moksha-marg) to other souls ( jainknowledge.com)

• Relation to the word “Jain”:

“Jain” = follower of the Jina. A Jain is one who has faith in the Jina and follows the path shown by them (right faith, right knowledge, right conduct). ( jainknowledge.com)

Both Digambar and Shwetambar agree on this meaning of “Jina” – a perfectly victorious, passionless, omniscient teacher who establishes the path to liberation.

You can read a bit more about Jina and related ideas like “Jinvani” and “Jai Jinendra” here:

• Meaning of “Jai Jinendra”
• What is Jinvani