Ok, what does the prefix "Inde" mean?
Is it actually two prefixes, "In" and "de," smashed together?
If it is, it looks redundant, since both mean roughly "non."
[Although later I guess I point out two separate, but related, forms of "non."]
Inde-fatigable describes something that cannot be fatigued.
Inde-finite describes something that has no finite boundary.
Here's the kicker though:
Inde-structable describes something that is not destructable.
My original guess was that indestructable has a different prefix than indefatigable; in-destructable vs. inde-fatigable.
But then I looked at the base word "destruct."
The antonym of "destruct" is "construct." Two words so similar suggest that, although this doesn't appear to be true now, "struct" used to be a word by itself. de-struct is to tear down a structure, and con-struct is to build a structure. So possibly struct is the root, and "de" and "con" are different prefixes used with the word "struct." And then by adding another prefix, "in," we are saying something is in-de-structable, or in-con-structable.
So what's the deal?