Emily Dickinson Lexicon

VIPER, n. [L. vipera; Fr. vipere; W. gwiber, from grib, a quick course, a driving, flying or serpentine motion, a wandering.]

1. A European serpent, the Vipera Berus, whose bite is venomous. Two harmless snakes are, in this country, called improperly by this name. A viper came out of the heat, and fastened on his hand. Acts xxix.
2. A person or thing mischievous or malignant. Shak.