A venomous snake.
The wicked are estranged from the womb: they go astray as soon as they be born, speaking lies. Their poison is like the poison of a serpent: they are like the deaf ADDER that stoppeth her ear; which will not hearken to the voice of charmers, charming never so wisely. ( Psalm 58:3-5 )
Bibliography Information"Entry for 'Adder'". A King James Dictionary.