प्रातिशाख्यम्prātiśākhyamA grammatical treatise laying down rules for the phonetic changes which words in any Śākhā of the Vedas…
A grammatical treatise laying down rules for the phonetic changes which words in any Śākhā of the Vedas undergo, and teaching the mode of pronouncing the accents etc. (There exist four Prātiśākhyas, one for the Śākala branch of Ṛigveda, one for each of the two branches of the Yajurveda, and one for the Atharvaveda.)