In Jainism, the term "palyopam" (or "palyopama") is a measure of an extremely long duration of time. The ayushya (lifespan) of celestial beings (devas) varies according to their class and region.

The Vyantar Devas (intermediary or peripatetic deities), who reside in the first heaven (Vyantar Viman), are described in Jain scriptures as having a lifespan of half a palyopam (ardha-palyopam). This is the standard lifespan for these devas as mentioned in texts such as the Jain Tattvartha Sutra and other canonical literature.

Summary:

• The class of devas with half a palyopam (ardha-palyopam) ayushya are the Vyantar Devas.