Diabolos is the Greek word for "devil". It has entered many languages to mean devil, such as Diabolus (Latin), Diavolo (Italian), Diablo (Spanish), Diable (French), and Diabo (Portuguese). Diabolos actually means "accuser" or "slanderer" and could also be connected to the Greek word diabolous, which means "divider" (which fits given Diabolos's affinity with gravity element in the Final Fantasy series), but eventually the general word Diabolos became the specific name of the entity. In the original Greek rendering, it was used to refer to the Christian Devil (The New Testament was written in Greek). Devil is the English translation of Diabolos and in Christian belief, this being is the embodiment of evil.
The concept of the Devil is believed to originate in Zoroastrianism with Angra Mainyu (also known as Ahriman) as well as from the Judaic Satan in the Book of Job in the Old Testament. Their Satan was merely the "devil's advocate", an angel who acted as a skeptic and whom God allowed to afflict Job with suffering. Satan is Hebrew for "prosecutor/accuser" or "adversary".
The concept of the summon Diabolos in Final Fantasy may be connected to the Jinn in Islamic mythology, similar to Ifrit. The djinn were the origins of genie myths and were spirits or ghosts made of fire or smoke. They were said to grant wishes.
See Special:Whatlinkshere/Etymology:Diabolos for a list of articles using this term.