वसन्तादिभ्यष्ठक्

Operational rule vidhi

The affix ठक् comes in the sense of 'who studies or who knows' after the words वसन्त etc.

Word by word (padaccheda)

Left context वसन्त- आदिभ्यः pañcamī · bahuvacanaSubstitute / term prathamā · ekavacana

Left context Pañcamī (5th case): "after X", the operation applies to what follows (1.1.67 तस्मादित्युत्तरस्य). Also used for limits and sources.
Substitute / term Prathamā (1st case): in operational rules, the substitute or the thing introduced; in definitions, the term or its referent.

Dotted words are technical terms. Hover or tap one to see its card.

Pink letters are it-markers (anubandhas), tags dropped by 1.3.9. Hover or tap one for the rule that marks it, or try the it-letter finder.

Full reading

वसन्त-आदिभ्यः ठक्

Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.

Commentary

The affix ठक् comes in the sense of 'who studies or who knows' after the words वसन्त etc.
This debars अण् ॥ As, वासन्तिकः 'who studies the book relating to Spring'. वार्षिकः &c ॥ 1 वसन्त, 2 वर्षा, 3 शरद्, 4 हेमन्त, 5 शिशिर, 6 प्रथम, 7 गुण, 8 चरम, 9 अनुगुण, 10 अपर्वन्, 11 अथर्वन् 12 ग्रीष्म,

Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.