viper

Etymology

From Middle French vipere, from Old French vipre, from Latin vīpera, contracted from vīvipara f (“viviparous”, adj.), from vivus (“alive”, adj.) + parere (“to bear”, verb). Doublet of weever and wyvern.

noun

1. A venomous snake in the family Viperidae.
2. (informal) Any venomous snake.
3. (figurative) A 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
4. (slang) A 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 (lyrics and music), “If You're a Viper”