Asmodeus (ˌæzməˈdiːəs; Ἀσμοδαῖος, Asmodaios) or Ashmedai (ˈæʃmᵻˌdaɪ; אַשְמְדּאָי, ʾAšmədʾāy; see below for other variations) is a prince of demons and hell. In Judeo-Islamic lore he is the king of both daemons (jinn/shedim) and demons (divs). Asmodeus is mostly known from the deuterocanonical Book of Tobit, in which he is the primary antagonist, or the Ars Goetia. In Peter Binsfeld's classification of demons, Asmodeus represents lust. The demon is also mentioned in some Talmudic legends; for instance, in the story of the construction of the Temple of Solomon. In Islam, he is identified with the "puppet" mentioned in the Quran.
The name Asmodai is believed to derive from the Avestan aēšma-daēva (𐬀𐬉𐬴𐬨𐬀𐬛𐬀𐬉𐬎𐬎𐬀, *aēṣ̌madaēuua), where aēšma means "wrath", and daēva signifies "demon". While the daēva Aēšma is thus Zoroastrianism's demon of wrath and is also well-attested as such, the compound aēšma-daēva is not attested in scripture. It is nonetheless likely that such a form did exist, and that the Book of Tobit's "Asmodaios" (Ἀσμοδαῖος) and the Talmud's "Ashmedai" (אשמדאי) reflect it. In the Zoroastrian and Middle Persian demonology, there did exist the conjuncted form khashm-dev (خشم + دیو), where both terms are cognates.
The spellings Asmoday, Asmodai, Asmodee (also Asmodée), Osmodeus, and Osmodai have also been used. The name is alternatively spelled in the bastardized forms (based on the basic consonants אשמדאי, ʾŠMDʾY) Hashmedai (חַשְמְדּאָי, Ḥašmədʾāy; also Hashmodai, Hasmodai, Khashmodai, Khasmodai), Hammadai (חַמַּדּאָי, Hammadʾāy; also Khammadai), Shamdon (שַׁמְדּוֹן, Šamdōn), and Shidonai (שִׁדֹנאָי, Šīdōnʾāy). Some traditions have subsequently identified Shamdon as the father of Asmodeus.
The Jewish Encyclopedia of 1906 rejects the otherwise accepted etymological relation between the Persian "Æshma-dæva" and Judaism's "Ashmodai" claiming that the particle "-dæva" could not have become "-dai" and that Æshma-dæva as such—a compound name—never appears in Persian sacred texts.