Aṣṭādhyāyī
The Aṣṭādhyāyī (Sanskrit: [ɐ.ʂʈaː.ˈdʰjaː.jiː], Devanagari: अष्टाध्यायी) is a grammar that describes a form of an early Indo-Aryan language: Sanskrit.
Authored by Sanskrit philologist and scholar Pāṇini and dated to around 500 BCE, it describes the language as current in his time, specifically the dialect and register of an élite of model speakers, referred to by Pāṇini himself as śiṣṭa. The work also accounts both for some features specific to the older Vedic form of the language, as well as certain dialectal features current in the author's time.
The Aṣṭādhyāyī employs a derivational system to describe the language, where real speech is derived from posited abstract utterances formed by means of affixes added to bases under certain conditions.
The Aṣṭādhyāyī is supplemented by three ancillary texts: akṣarasamāmnāya, dhātupāṭha and gaṇapāṭha.