Lexical Definition

‎ἔχιδνα‎ échidna (ekh'-id-nah) snake G:N-F
of uncertain origin

viper.

Usage: 2 forms in 5 verses
Form Translated As     In Verse(s)
ἔχιδνα a viper Acts.28.3
ἐχιδνῶν of vipers Matt.3.7Matt.12.34Matt.23.33Luke.3.7

Abbott-Smith

** ἔχιδνα, -ης, ἡ, [in OT (Aq.), Is 59:5*;]
a viper: Ac 28:3; metaph., γεννήματα ἐχιδνῶν, Mt 3:7 12:34 23:33, Lk 3:7.†

Abbott-Smith References

Book Refs
Isaiah 59:5
Matthew 3:7 · 12:34 · 23:33
Luke 3:7
Acts 28:3

Liddell-Scott-Jones

ἔχιδνα-α, ,

(ἔχις) viper, [Refs 5th c.BC+]; probably of a constrictor snake, [NT+5th c.BC+]; ἱματισμένη ., of woman, [Refs 2nd c.AD+]; γεννήματα ἐχιδνῶν brood of vipers, term of reproach, in [NT]

__II proper name of a monster, [Refs 8th c.BC+]

LSJ Scripture Refs: Acts.28.3Matt.3.7