Avarśpini (also written avasarpiṇī) is the descending half of the Jain time cycle (Kalachakra). In this half-cycle, conditions in the world gradually decline—moral conduct, spirituality, lifespans, and overall well‑being decrease over many ages. This is the natural, repeating pattern in Jain cosmology, which alternates with its ascending half, utsarpiṇī. ( jainknowledge.com)

Key points in simple terms:

• It is the downward phase of time, after the previous rising phase, and before the next rising phase begins again. ( jainknowledge.com)
• It is divided into six eras (aras), each one progressively more challenging for spiritual practice. The current era in many Jain texts is the fifth ara, called duḥṣamā, during which lifespan and virtue decline further. ( jainknowledge.com)
• In both Digambara and Śvetāmbara traditions, the framework is the same: avasarpiṇī describes a long, cyclical period of decline, with Tirthankaras appearing across eras to revive dharma, including Mahavira in this cycle. Differences today are mainly in chronology and details, not in the overall idea. ( jainknowledge.com)

Simple summary you can use:

• Avasarpini/avarspini = descending half of the wheel of time; world grows more difficult, dharma wanes, life spans shorten as the ages pass. We are said to be in the fifth era of this descending cycle. ( jainknowledge.com)

You can read more on these definitions here:

• avasarpini means what?
• concept of avasarpini and utsarpini kaal
• explain each part of avasarpini

Note: If you need the exact shakha-specific details (Digambara vs. Śvetāmbara chronologies), tell me and I can outline the differences clearly.