Incunabula
This refers to printed material from Europe prior to the 1500s. (It’s the plural form; the singular is “incunabule.”)
The etymology is from a Latin word meaning “swaddling clothes,” which refers to the “infancy” of printing during this period. (Gutenberg invented the printing press in the 1430s.)
Dictionary.com offers an alternate, more generalized definition:
the earliest stages or first traces of anything.
In this sense, it reminds me of Antediluvian, which literally means a time period before the Great Flood of the Old Testament, but has come to mean, simply, something very old.
Why I Looked It Up
I think it came up a lot in Cloud Cuckoo Land.
Then, in Conspiracies and Secret Societies, it was used to identify the inner circle of participants in the secretive Bilderberg Meetings.
Postscript
Added on
From Once Upon a Tome:
With a smile that did not reach his eyes, he began to shed books everywhere, in a determined fashion that didn’t brook arguments. As he did so, he launched into a breathless diatribe about how important these incunabula were…