Sabellian or Osco-Umbrian is one of the two subgroups into which the Italic branch of the Indo-European language family is divided, the other being Latino-Faliscan. Despite their many similarities in nominal and verbal inflection and syntax, the actual relationship between Sabellian and Latino-Faliscan has always been a matter of debate.
Initially, several linguists, such as Antoine Meillet, Henri d’Arbois de Jubainville and Carl Darling Buck, were in favour of postulating the existence of one Italic branch, but this theory was soon rejected by Alois Walde, Vittore Pisani, Giacomo Devoto and, more cautiously, by Madison Scott Beeler, who all subscribed to the view that Italic never existed as such, but rather that it originated as a result of contact within Italy.
Recently, however, the notion of the original unity of Italic peoples has been gaining ground in the scholarly community (but not among Italian linguists) and it is now regarded as the standard view on the issue.
As shown by Helmut Rix, one of the main problems concerning Italic is determining whether it is possible to reconstruct Proto-Italic or Common Italic as an intermediate stage between Proto-Indo-European and the languages in question.