Isadore

Isadore is a masculine English spelling variant of Isidore. Its deeper source is ancient Greek Ἰσίδωρος (Isidōros), a two-part theophoric name conventionally translated as “gift of Isis.” The spelling Isadore is English, but the name’s linguistic roots are Greek; it is not an originally English compound.

Reference dictionaries give the usual English pronunciation as approximately IZ-uh-dor. Webster’s New World College Dictionary treats Isadore and Isador as variants of Isidore, while the dedicated Isadore entry in Dictionary.com likewise classifies it as a masculine given name. (Webster’s New World via Collins; Dictionary.com)

Meaning and Linguistic Formation

The Greek name Ἰσίδωρος joins Isis, the Greek form of the Egyptian goddess’s name, to Greek δῶρον (dōron), “gift.” It therefore belongs to the large class of ancient theophoric names: names formed with the name of a deity. “Gift of Isis” is the literal analysis of the historical name elements, not a claim about the religion, ancestry, or beliefs of a modern bearer. The University of Oxford’s Lexicon of Greek Personal Names describes Ἰσίδωρος as a common Greek name and identifies the same meaning. (Lexicon of Greek Personal Names; Ainiala, Saarelma and Sjöblom, *Names in Focus*, pp. 145–48)

The broad language path is:

• ancient Greek Ἰσίδωρος (Isidōros);
• Latin Isidorus;
• English and French Isidore;
• English variants Isadore and Isador.

This sequence explains the name’s etymology, but it does not date the first use of the Isadore spelling. The reference works checked for this page identify it as an English variant but do not establish a single inventor, first bearer, or moment when i changed to a. It is therefore safer to describe Isadore as a later spelling variant than to attribute it to a particular clerk, migration event, or pronunciation shift.

From an Ancient Name to a Christian Name

Greek names did not pass into English by an unbroken line of everyday use. The Oxford Lexicon of Greek Personal Names explains that saints, martyrs, Latin forms, and other European languages commonly provided the intermediate route. For Isidore, saints associated with Spain were especially important to that later transmission. (Lexicon of Greek Personal Names)

The best-known was Isidore of Seville, the scholar and bishop who succeeded his brother Leander as bishop of Seville in 599 and died in 636. His prominence helped make the inherited pagan-era name usable within Christian naming traditions. That survival does not change the word’s original reference to Isis; it shows that personal names can remain in use after their first religious setting has changed. (Holy See, “Saint Isidore of Seville,” 18 June 2008)

The name was not confined to western Europe. The University of Warsaw’s Database of Medieval Nubian Texts records a Greek Isidoros / Eisidōros in a text from Sakinya, broadly dated 700–999, and classifies it there as a Christian male name associated with saints called Isidore. This is evidence for medieval use of the underlying name, not for the English spelling Isadore and not for descent between any bearers. (DBMNT, IM Reference 2692)

Isidor in Eastern European Jewish Naming

The name also entered a distinct Jewish naming context. Onomastician Alexander Beider explains that, from the 1830s, German civil names became increasingly common among Jews in Eastern Europe. He gives Isidor alongside Isroel as one example of a German name used in relation to an existing Jewish personal name. This was a social and administrative naming practice, not a new Hebrew etymology for Isidor. (Alexander Beider, “Names and Naming,” *YIVO Encyclopedia of Jews in Eastern Europe*, 2010)

That history helps explain why records for one person or family may contain Isidor, Isidore, or Isadore, especially after a move into an English-speaking setting. It does not mean that every Isadore was Jewish, that Isadore literally translates Israel, or that any two bearers share a community or lineage. The Greek etymology and a person’s Hebrew or Yiddish name are separate questions.

Related Forms and How to Compare Them

• Isidore is the main English and French form from which English Isadore is treated as a variant.
• Isador is another English variant.
• Isidor is used in German and several central or eastern European naming traditions; it is also the form discussed by YIVO in Jewish civil naming.
• Isidoro and Isidro are related forms used in several Romance-language traditions.
• Isidora and Isadora are feminine members of the same name family, not merely interchangeable spellings of masculine Isadore.
• Izzy can be a familiar form of Isidore or Isadore, but it is also used for other names. A nickname alone cannot identify a person’s formal name.

These forms share an etymological family, but language-specific forms should not be silently standardized in historical records. Preserve the spelling actually supplied by each source and use dates, relatives, and locations to decide whether differently spelled records concern the same person. A concise overview of the cross-language forms is available in the editorial name database Behind the Name. (“Isadore”; “Isidore”)

U.S. Usage and Popularity

The U.S. Social Security Administration’s national baby-name files show that Isadore was used predominantly for boys and was most visible in the early twentieth century, with its strongest period in the 1910s before a marked decline. It is now outside the frequently published top 1,000. The important methodological point is that the SSA counts Isadore, Isidore, and Isador separately; combining them changes the result and should be stated explicitly. (SSA, “Popular Baby Names: Beyond the Top 1000 Names”)

Those figures are evidence about recorded U.S. births, not worldwide distribution. The SSA derives the series from Social Security card applications for U.S. births after 1879 and warns that coverage is incomplete for many people born before 1937. It also suppresses name-and-year results with fewer than five recorded occurrences. (SSA, “Background Information for Popular Names”)

Given Name, Surname, and Identity

Isadore is chiefly documented and defined as a given name. It can also occur in a surname field, but the personal-name meaning “gift of Isis” does not by itself explain how a particular hereditary surname arose. A surname may have developed from an ancestor’s given name, from a later spelling change, or through another documented naming process. That family history must be established from records rather than inferred from the ancient Greek meaning.

Similarly, the name alone does not prove Egyptian or Greek ancestry, devotion to Isis, Christian affiliation, or Jewish identity. Its history includes more than one route of cultural adoption, and parents may have chosen it for a saint, a relative, its sound, or another reason that only family evidence can establish.

References

• Terhi Ainiala, Minna Saarelma and Paula Sjöblom, Names in Focus: An Introduction to Finnish Onomastics, translated by Leonard Pearl, Finnish Literature Society, first published 2012; digital edition 2016, especially pp. 145–48. Library of Congress-hosted PDF
• Alexander Beider, “Names and Naming,” YIVO Encyclopedia of Jews in Eastern Europe, 12 February 2010. YIVO Encyclopedia
• Lexicon of Greek Personal Names, “Greek Names in English,” University of Oxford. LGPN
• Database of Medieval Nubian Texts, IM Reference 2692, University of Warsaw. DBMNT
• Benedict XVI, “Saint Isidore of Seville,” General Audience, 18 June 2008, Libreria Editrice Vaticana. Holy See
• Webster’s New World College Dictionary, 5th digital edition, “Isidore,” hosted by Collins, 2025. Collins Dictionary
• Dictionary.com Unabridged, “Isadore,” based on the Random House Unabridged Dictionary, 2023. Dictionary.com
• Social Security Administration, “Popular Baby Names: Beyond the Top 1000 Names” and “Background Information for Popular Names,” data updated March 2026. National data and limits; methodology
• Mike Campbell, “Isadore” and “Isidore,” Behind the Name, entries updated 1 December 2024 and 26 May 2026. Isadore entry; Isidore entry