In Jain Dharma, “Jyotirloka” generally means the region of Jyotiṣka Dev – the luminous / stellar devas.

What is there in Jyotirloka?

In Jyotirloka stay the devas who are connected with light and celestial bodies, such as:

1. Sūrya – Devs of the suns
2. Chandra – Devs of the moons
3. Graha – Devs of the planets
4. Nakṣatra – Devs of the constellations
5. Tārā – Devs of the scattered stars

All these together are called Jyotiṣka deva, and their region is called Jyotirloka.

Some important points according to Jain cosmology:

• Jyotirloka is in Madhya Loka (the middle world), above our earthly region.
• These devas are not creators of the universe and not liberated;

they are also bound by karma, enjoy celestial pleasures for a long time, and then must again take birth in other gatis (human, animal, hell etc.).

• Their continuous movement around Mount Meru is used to determine time

(day–night, months, years etc.) in Jain cosmology.

So, in short: Jyotirloka = the region of luminous devas who reside in and preside over the sun, moon, planets and stars.

You can read a simple explanation of the four types of Dev (including Jyotishka) here