What does the phrase “A nest of vipers” mean?
Congregating together is a gang of evildoers.
What does the expression “den of vipers” mean?
Although the phrase “a nest of vipers” is figurative, its literal meaning isn’t too far off. In English, calling someone a “snake” has long been considered offensive. This comes from the snake’s ungratefulness or treachery in Aesop’s fable. The farmer and the snake is a story about how a farmer saved a snake from freezing to death, only for the serpent to bite the farmer fatally once it had recovered. Because of their reclusive nature, snakes have a reputation for being suspicious and posing a threat. Vipers, sometimes known as adders, were singled out as particularly vile since they were toxic, unlike other English snakes. Someone would be severely insulted if they were called a viper. This particular slur has been around since at least the 16th century. In Matthew 3, William Tyndale used the term “vipers” as a figurative insult. den of vipers
O generation of vipers, who taught you to run away from the coming retribution? he said to them.
Later, in The Art of Conny Catching, 1591, Robert Greene used the phrase even more forcefully:
Being rejected by God, worldly vipers, and an excremental manifestation of sin, these vicious snakes are unworthy of the name of men.
Since roughly the same time, groups of people—typically those with evil intentions—have been referred to as “nests.” The phrase “den of vipers” first appeared in print in 1644, when it appeared in the title of a pamphlet denouncing a group of conspirators who were preparing to treason against the English Parliament.