According to the historian Jorge Lardé y Larin, Izalco comes from the roots itz (obsidian); cali (house), and co (place), which translates to city of obsidian houses. It is said that the primitive name was tecupan ishatcu, which means seat of the lords in a place of crystal waters; or the land was also known as muchishatcu which means kingdom of the Izalcos.