नखमुखात् संज्ञायाम्

Operational rule vidhi

The feminine affix ङीष् is not used after 1. नख 2. मुख when (the word at the end of which they stand) is a Name.

Word by word (padaccheda)

Left context नख- मुखात् pañcamī · ekavacanaRight context संज्ञायाम् saptamī · ekavacana

Left context Pañcamī (5th case): "after X", the operation applies to what follows (1.1.67 तस्मादित्युत्तरस्य). Also used for limits and sources.
Right context Saptamī (7th case): "when X follows", the operation applies to what precedes (1.1.66 तस्मिन्निति निर्दिष्टे पूर्वस्य). Also a condition or domain ("in the sense of").

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Full reading

नख-मुखात् संज्ञायाम्

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

Commentary

The feminine affix ङीष् is not used after 1. नख 2. मुख when (the word at the end of which they stand) is a Name.
Thus शूर्प + नखा, = शूर्पणखा, 'Surpanakha the sister of Ravana'. The न् is changed into ण् by 8.4.3 (पूर्वपदात् संज्ञायामगः) ॥ So also वज्रणखा, गौरमुखा, कालमुखा &c. Why do we say 'when denoting a Name'? Witness ताम्रमुखी कन्या 'a copper-faced damsel', or चन्द्रमुखी 'moon-faced'.

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