8.3.66
सदिरप्रतेः
Operational rule vidhi
The स् of सद् is changed to ष after an उपसर्ग (Preposition) having an इ or उ , but not after प्रति.
Word by word (padaccheda)
Substitute / term सदिः prathamā · ekavacanaLeft context अप्रतेः pañcamī · ekavacana
- Substitute / term Prathamā (1st case): in operational rules, the substitute or the thing introduced; in definitions, the term or its referent.
- Left context Pañcamī (5th case): "after X", the operation applies to what follows (1.1.67 तस्मादित्युत्तरस्य). Also used for limits and sources.
Dotted words are technical terms. Hover or tap one to see its card.
Full reading
सदिः अप्रतेः
Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.
Commentary
The स् of सद् is changed to ष after an उपसर्ग (Preposition) having an इ or उ , but not after प्रति।
The word सदिः is in the first case, but has the force of genitive. Thus निषीदति, विषीदति, न्यषीदत्, व्यषीदत् ॥ निषसाद, विषसाद ॥ The second स remains unchanged in the Perfect by 8.3.118.
Why do we say 'but not after प्रति'? Observe प्रतिसीदति ॥ Prof. Bohtlingk points out that the sutra is सदेरप्रतेः as given by Sayanacharya in his commentary on Rig Veda VI.13. I.Panini, however, often uses the first case with the force of the Genitive, as in 8.3.80.
Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.