घ्वसोरेद्धावभ्यासलोपश्च

Operational rule vidhi

The घु-संज्ञक verb roots and the verb root अस् get an एकार as आदेश when followed by the 'हि' प्रत्यय. Also, अभ्यास, if present, is removed.

Word by word (padaccheda)

Target - असोः ṣaṣṭhī · dvivacanaSubstitute / term एत् prathamā · ekavacanaRight context हौ saptamī · ekavacanaSubstitute / term अभ्यासलोपः prathamā · ekavacanaIndeclinable च avyaya

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.
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").
Indeclinable An avyaya such as च "and", वा "optionally", न "not".

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

Full reading

-असोः एत् हौ अभ्यासलोपः च

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)

- असोः → एत् अभ्यासलोपः / हौ

Replace ghu-asoḥ with et abhyāsalopaḥ when hau follows. Inherited words (anuvṛtti) may add further conditions.

Commentary

For the final vowel of the roots दा and धा (धु) and for the स् of अस् , is substituted ए before the Imperative ending हि and thereby the reduplicated syllable of दा and धा (धु) is elided.
Thus देहि, and धेहि, of घु, and एधि of अस्, the स being elided by this sutra, and अ being elided by 6.4.111. This लोप of the present sutra should be considered as having an indicatory श् so that the whole of the reduplicated and not only the final letter of the abhyasa 1.1.55 is elided.

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