Answer

The word is Jai.

Jai means victory, glory, or honor. In Jain Dharma, people often say:

• Jai Jinendra — “Victory/glory to the Jinendra”

Here, Jinendra means the Jina or enlightened conqueror — one who has conquered inner enemies like anger, ego, deceit, and greed.

Explanation

In Jain tradition, the word Jai is used respectfully to express reverence, not worldly victory. It means honoring the spiritual victory of the Tirthankars and Arihants.

Takeaway

The best Jain word starting with J meaning “victory” is Jai, especially in the phrase Jai Jinendra.