G2191
ἔχιδνα
snake
ἔχιδνα, -ης, ἡ [in OT (Aq.), Isa.59:5 * ;] a viper: Act.28:3; metaphorically, γεννήματα ἐχιδνῶν, Mat.3:7 12:34 23:33, Luk.3:7.† (AS)
The KJV translates G2191 in the following manner:
vipers (8x), viper (2x)
Full Thayer's lexicon entry
ἔχιδνα — échidna
ἔχιδνα, ἐχιδνης, ἡ, a viper: Act 28:3 (Hesiod, Herodotus, Tragg., Aristophanes, Plato, others); γεννήματα ἐχιδνῶν offspring of vipers (anguigenae, Ovid, metam. 3,531), addressed to cunning, malignant, wicked men: Mat 3:7; Mat 12:34; Mat 23:33; Luk 3:7.
5 occurrences
Matthew (3), Luke (1), Acts (1)