The etymology of the name is uncertain. The spelling Ἀπόλλων (pronounced [a.pól.lɔːn] in Classical Attic) had almost superseded all other forms by the beginning of the common era, but the Doric form Apellon (Ἀπέλλων), is more archaic, derived from an earlier *Ἀπέλjων. It probably is a cognate to the Doric month Apellaios (Ἀπελλαῖος), and the offerings apellaia (ἀπελλαῖα) at the initiation of the young men during the family-festival apellai (ἀπέλλαι). According to some scholars the words are derived from the Doric word apella (ἀπέλλα), which originally meant "wall," "fence for animals" and later "assembly within the limits of the square." Apella (Ἀπέλλα) is the name of the popular assembly in Sparta, corresponding to the ecclesia (ἐκκλησία). R. S. P. Beekes rejected the connection of the theonym with the noun apellai and suggested a Pre-Greek proto-form *Apalyun.

What is the name of the popular assembly in Sparta?