थो न्थः

Operational rule vidhi

The थकार of the words पथिन् तथा मथिन् get the 'न्थ्' आदेश in presence of a सर्वनामस्थान.

Word by word (padaccheda)

Target थः ṣaṣṭhī · ekavacanaSubstitute / term न्थः prathamā · ekavacana

Target Ṣaṣṭhī (6th case): names what gets replaced, "in place of X" (1.1.49 षष्ठी स्थानेयोगा).
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.

थः न्थः

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

As a rewrite rule (sketch from case endings)

थः → न्थः

Replace thaḥ with nthaḥ. Inherited words (anuvṛtti) may add further conditions.

न्थ् is substituted for the थ् of 1. पथिन् and 2. मथिन् in the strong cases.
As पन्थाः, पन्थानौ, पन्थानः, मन्थाः, मन्थानौ, मन्थानः ॥

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