Is there a term for borrowings from a language’s own proto-language?

There’s lots of these—Modern Greek from Ancient Greek, Russian from Old Church Slavonic—but I’m not aware of a generic term. In Greek. for example, these are referred to as learnèd loans (λόγιο δάνειο)—but a learned loan in English is a loan from Latin, not Old English. (In fact we do have a term for learned loans in English: inkhorn terms.)

Such borrowings are often the result of linguistic purism, which seeks to use “native” lexical resources instead of foreign terms. But purism isn’t the only motivation for them, so I wouldn’t call them purisms…