Strong's:ἔχιδνα an adder or other poisonous snake (literally or figuratively)Derivation: of uncertain origin;KJV Usage: viper.
TBESG:ἔχιδναsnakeG:N-F ἔχιδνα, -ης, ἡ [in OT (Aq.), Isa.59:5 * ;] a viper: Act.28:3; metaph., γεννήματα ἐχιδνῶν, Refs Mat.3:7 12:34 23:33, Luk.3:7.† (AS)
ἔχιδνα echidna ekh'-id-nah Of uncertain origin; an adder or other poisonous snake (literally or figuratively)KJV Usage: viper.