आदाचार्याणाम्

Operational rule vidhi

According to the opinion of other Teachers, आ is substituted for the which is obtained by shortening the long आ of the feminine (under sūtra केऽणः (7.4.13)) of a word which has no corresponding masculine form.

Word by word (padaccheda)

Substitute / term आत् prathamā · ekavacanaTarget आचार्याणाम् ṣaṣṭhī · bahuvacana

Substitute / term Prathamā (1st case): in operational rules, the substitute or the thing introduced; in definitions, the term or its referent.
Target Ṣaṣṭhī (6th case): names what gets replaced, "in place of X" (1.1.49 षष्ठी स्थानेयोगा).

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

Full reading

आत् आचार्याणाम्

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)

आचार्याणाम् → आत्

Replace ācāryāṇām with āt. Inherited words (anuvṛtti) may add further conditions.

Commentary

According to the opinion of other Teachers, आ is substituted for the which is obtained by shortening the long आ of the feminine (under sūtra केऽणः 7.4.13) of a word which has no corresponding masculine form.
As खट्वाका, अखट्वाका or परमखट्वाका ॥

Note: The "Teachers" referred to here are either those other than the Northern Grammarians, or it may refer to the Teacher of Panini, the plural being for the sake of respect. Thus there are three forms अखट्वका, अखट्विका, and अखट्वाका ॥

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