तेन निर्वृत्तम्

Operational rule vidhi

To indicate the name of a country by referring to its creator, an appropriate तद्धित प्रत्यय gets attached to the word in तृतीयाविभक्ति representing the name of the creator.

Word by word (padaccheda)

With / by तेन tṛtīyā · ekavacanaSubstitute / term निर्वृत्तम् prathamā · ekavacana

With / by Tṛtīyā (3rd case): accompaniment or means.
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.

Full reading

तेन निर्वृत्तम्

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

Commentary

After a word in the Instrumental -3rd case in construction an affix is added in the sense of 'completed by him' when the whole word so formed is the name of a country.
The phrase देशे तन्नाम्नि of the last sutra governs this and the two subsequent sutras. By these four sutras the names of countries are formed from various substantives. Thus कुशाम्बेन निर्वृत्ता = कौशाम्बी नगरी "the city of Kausambi, completed by Kusamba". Similarly साहस्री परिखा "a mote completed by a thousand (gold coins) or persons". A place is named after the means or the person, by which or through whom it is established.

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