viper /(vī"pẽr)/

vi·per

viper

n.
  1. Any one of numerous species of Old World venomous snakes belonging to Vipera, Clotho, Daboia, and other genera of the family Viperidae. (Zool.)
    There came a viper out of the heat, and fastened on his hand.
    — Acts xxviii. 3.
  2. A dangerous, treacherous, or malignant person.
    Who committed To such a viper his most sacred trust Of secrecy.
  3. Loosely, any venomous or presumed venomous snake.

Phrases & Compounds
Horned viper
See Cerastes.
Red viper
the copperhead.
Viper fish
a small, slender, phosphorescent deep-sea fish (Chauliodus Sloanii). It has long ventral and dorsal fins, a large mouth, and very long, sharp teeth.
Viper's bugloss
a rough-leaved biennial herb (Echium vulgare) having showy purplish blue flowers. It is sometimes cultivated, but has become a pestilent weed in fields from New York to Virginia. Also called blue weed.
Viper's grass
a perennial composite herb (Scorzonera Hispanica) with narrow, entire leaves, and solitary heads of yellow flowers. The long, white, carrot-shaped roots are used for food in Spain and some other countries. Called also viper grass.