viper

plural vipers

1. A venomous snake in the family Viperidae.

   Synonyms: adder

2. informalAny venomous snake.
3. figurativelyA dangerous, treacherous, or malignant person.

   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

   2 more examples

   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[ohn] M[acock] for John Starkey […], →OCLC, page 62

   Then there's the heterosexual, open-mined ^([sic]) entourage who loves us dearly and are our best friends. They laugh at our humor and understand our sorrow. For they are rare and unique in prison. But the vipers always ruin things. They refer to our straight friends as "Closet-Cases," "Undercovers," and "Flip-Floppers."

   1990 December 16, Gianni Comes, “Not Just Homophobia”, in Gay Community News, volume 18, number 22, page 4

4. slangA person who smokes marijuana.

   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, “If You're a Viper”