This paper focuses on the early interactions, in medieval India, between the traditions of Pan. inian grammar (Vyakaran. a) and Vedic exegesis (Mımamsa) on the definitions of the sentence (vakya). The first section discusses the origins of the debate in ancient grammar, and highlights the existence of a conflict between two of its most prominent authorities: Pan. ini (4th century BC) and Katyayana (3rd century BC). A second section deals with the contribution to this debate made by Bhartr̥hari (5th century AD), the author of the Vakyapadıya (“A Treatise on the Word and the Sentence”). It is shown that Bhartr̥hari, even while claiming to reconcile Pan. ini and Katyayana,  introduces into Vyakaranaa definition of the sentence on a semantic (and not merely formal) basis, which he borrows from Vedic exegesis. This borrowing appears as a preliminary to his own theorisation of the sentence as “undivided” (akhanda) in the Vakyakanda.