ἔχιδνα

Derivation

of uncertain origin;

Meaning

an adder or other poisonous snake (literally or figuratively)

In the King James Version

viper

Translated as

vipers (4), viper (1)

Where it appears

Found in 5 verses

Matthew

3:7, 12:34, 23:33

Luke

3:7

Acts

28:3