It's reasonably *assumed* to be a variant of
Isidora.
Two of my pet issues coincide right here:
Isadora vs
Isidora, and facts vs expert consensus.
The etymological meaning of a modern usage depends on what you accept as evidence of etymology.
Etymology, being history and not science, does not always have facts. It has information that is judged to be more or less useful, and consensus about the judgment. We generally appeal to people who study etymology, for their judgment, and consensus on it. That is usually the best way to decide and to agree on "facts." But it doesn't make our information more *factually* true, just because experts agree.
There does not appear to be any evidence demonstrating directly that the name
Isadora originated, in fact, as a variant or misspelling of
Isidora. It's a judgment of what seems most reasonable and likely.
(If anyone knows of historical evidence of an "originating" usage of
Isadora, that was meant as a variant of
Isidora, they could contradict me)
So no one knows for sure whether the original usage(s) of
Isadora was meant to be the same name as
Isidora, and only the spelling was changed; or whether the giver of the name intended to combine, say,
Isabella and
Theodora, that happened to coincide closely with
Isidora. If it happened to be the latter, nobody today would know.
(my opinion: it seems most likely to me, personally, that the name was probably supposed to be taken to be
Isidora, and the spelling was influenced by
Isabella. I don't think people just decided to fancifully put an 'a' there, because
Isidore was a saint name. I think the existence and popularity of the name
Isabella probably made it seem more legit to change
Isidora to
Isadora. It's possible also, that Isidore/a had some kind of cultural connotations that Isadora-namers wanted to distance themselves from, and changing it to be more like
Isabella, seemed to do the trick.)
If someone today wanted to name a child
Isadora, they could say that it was a variant of
Isidora and cite Behind the Name as the "fact check" demonstrating that it "really IS" a variant of
Isidora.
That's not really a fact check, though, it's a consensus check, an appeal to the authority of experts. It's the best we can do, but it's not a fact based on the same quality of information we have, when we say that "
Isidora means 'gift of
Isis."
A parent naming a child
Isadora today could also say that, in the case of their child at least, it was a combination of
Isabella and
Theodora - and they could not be technically wrong about that. But they'd have a hard time arguing with people who insisted that it was a variant of
Isidora.
- mirfak