Unlike most of the terms on this list, “generation of vipers” has a documented, and quite famous, literary origin. The phrase appears in the King James Bible, used as a sharp rebuke, John the Baptist and later Jesus both use it, in the Gospels of Matthew and Luke, aimed at religious leaders accused of hypocrisy. It’s meant as an insult, likening the target to a brood of venomous snakes, deceptive and dangerous.
Over the centuries, the phrase drifted from pure insult into general usage as a stand-in collective noun for vipers themselves, likely because it was already such a memorable, widely known pairing of words. It’s a good example of how not every collective noun grew out of medieval hunting vocabulary or careful naturalist observation; some, like this one, came from literature and stuck around simply because they were too vivid to forget.
Biologically, it still points to the same real behavior as “nest,” vipers sharing dens, birthing sites, or overwintering shelters, just dressed in far more dramatic language.
Example: “The old preacher’s line about a generation of vipers stuck with the whole congregation.”
Related: Collective Nouns for Reptiles · What Is a Group of Vipers Called?