Definition of "viper"

And aggravate my folly who committed / To ſuch a viper his moſt ſacred truſt / Of ſecreſie, my ſafety, and my life.

1671, John Milton, “Samson Agonistes, […]”, in Paradise Regain’d. A Poem. In IV Books. To which is Added, Samson Agonistes, London: […] J. M[acock] for John Starkey […], page 62

Consider, for the love of Heaven, to what you run madly: will you take this viper into your bed?

1879, Francis Beaumont, The Works of Beaumont and Fletcher: The Text Formed from a New Collation of the Early Editions, Volume 1, D. Appleton, page 350

Dreamed about a reefer five feet long / Mighty Mezz, but not too strong / You'll be high but not for long / If you're a viper

a. 1936, Stuff Smith (lyrics and music), “If You're a Viper”