From Greek 'Isidoros' meaning gift of Isis, combining the Egyptian goddess with Greek 'doron' (gift).
Isadore is a variant of Isidore, one of the great names of antiquity, derived from the Greek "Isidoros" — a compound of "Isis," the Egyptian goddess of wisdom, magic, and motherhood, and "doron," meaning gift. The name thus means, beautifully, "gift of Isis," and it passed into the Greco-Roman world as the Hellenistic cultures of the Mediterranean absorbed Egyptian religion and iconography. It was a cosmopolitan name from its very origin, spanning the border between Egyptian mythology and Greek language.
The name's most celebrated early bearer was Saint Isidore of Seville, the seventh-century Spanish bishop and encyclopedist whose "Etymologiae" was one of the most widely read books of the entire Middle Ages — a twenty-volume attempt to compile all human knowledge into a single work. He is now the patron saint of the internet, a designation that delights those who know the history. Isidore of Miletus was the architect of the Hagia Sophia in Constantinople.
The name traveled into European Jewish communities as Isadore and Isidor, becoming particularly common in Ashkenazi culture in the nineteenth and early twentieth centuries as a learned, classical-sounding choice that bridged secular and religious identity. Isadore sits today in a fascinating liminal space: old enough to feel genuinely antique, obscure enough to feel distinctive, and carrying a mythological weight — the gift of Isis — that makes it resonant for parents drawn to names with deep cultural and historical layers. The variant spelling Isadore has a slightly more informal, American feel than the classical Isidore.