Śākaṭāyana is a Sanskrit grammarian of Iron Age India (fl. roughly 8th c. BCE). His work is referred by scholars such as Yaska (around 7th c. BCE) and Pāṇini (circa 5th c. BCE), as well as other Sanskrit grammarians, but is lost to us today.
He claimed that all nouns are ultimately derived from some verbal root. This refers to the origin of names of things, or nouns. To cite an English example, the noun origin derives etymologically from the Latin originalis, ultimately derived from the verb oriri, "to rise". An example of a morphological derivative might be the noun hitter - derived from the verb hit.
This process is reflected in the Sanskrit grammar as the system of krit-pratyayas or verbal affixes.
In his The word and the world, the philosopher Bimal Krishna Matilal refers to this debate (which lasted several centuries) as an
interesting philosophical discussion between the nairuktas or etymologists and the pāṇinīyas or grammarians. According to the etymologists, all nouns (substantives) are derived from some verbal root or the other. Yāska in his Nirukta refers to this view (in fact defends it) and ascribes it to an earlier scholar Śākaṭāyana. This would require that all words are to be analysable into atomic elements, 'roots' or 'bases' and 'affixes' or 'inflections' — better known in Sanskrit as dhātu and pratyaya [...] Yāska reported the view of Gārgya who opposed Śākaṭāyana (both preceded Pāṇini who mentions them by name) and held that not all substantival words or nouns (nāma) were to be derived from roots, for certain nominal stems were 'atomic'.[1](p. 8-9)
Sakatayana also proposed that functional morphemes such as prepositions do not have any meaning by themselves, but contribute to meaning only when attached to nouns or other content words:
His text may have been called the Lakṣaṇa Śāstra, in which he also describes the process of determining gender in animate and inanimate creation.
Not much is known about Sākatāyana's life, but it is accepted that he lived in Gandhara, what is today the vicinity of Peshawar.