Paliyopama, or Palyopam, is a very large Jain unit of time used to express an unimaginably long duration.

Traditional Jain description

It is defined by a simile:

• Imagine a huge pit, 1 yojana long, 1 yojana wide, and 1 yojana deep.
• Fill it completely with fine hairs.
• If one hair is removed every 100 years, the time taken to empty that pit is called one Palyopama.

Meaning

So, Palyopama = an extremely vast measure of time, far beyond ordinary human calculation.

Jain usage

It is used in Jain scriptures to describe:

• long periods in cosmology
• the duration of samsara
• the lifespan of beings in certain realms

If you want, I can also give the other Jain time units like samaya, avali, muharta, aavarta, and sagaropama in simple order.