The Aequi (Ancient Greek: Αἴκουοι and Αἴκοι) were an Italic tribe on a stretch of the Apennine Mountains to the east Latium in central of Italy who appear in the early history of ancient Rome. After a long struggle for independence from Rome they were defeated and substantial Roman colonies were placed on their soil. Only two inscriptions believed to be in the Aequian language remain. No more can be deduced than that the language was Italic. Otherwise the inscriptions from the region are those of the Latin-speaking colonists in Latin. The colonial exonym documented in these inscriptions is Aequi and also Aequicoli ("colonists of Aequium"). The manuscript variants of the classical authors present Equic-, Aequic-, Aequac-. If the form without the -coli is taken as an original, it may well also be the endonym, but to date further evidence is lacking.
The historians made many entries concerning the wars between the Aequi and Rome; the geographers scarcely mention them. Pliny the Elder and Ptolemy both make the same brief statement: the towns of the Aequiculi were Cliternia or Cliternum and Carsoli or Carsioli respectively. Pliny places them in Augustus' Regio IV; Ptolemy adds that they were to the east of the Sabini. By the time of the early Roman Empire, all vestige of the Italic Aequi was gone. The two cities mentioned had been Roman colonies. The forms mentioned in inscriptions from there are Carsioli and Cliternia.
They occupied the upper reaches of the valleys of the Aniene, Tolenus and Himella, the last two being mountain streams running northward to join the Nera river.