poison, rust

Concise Bible Dictionary:

The poison of serpents and of asps is used in scripture symbolically for the judgment of God and for the malignity inherent in the wicked ({vi 5783;5792}Deut. 32:24,33; Job 6:4; Job 20:16; Psa. 58:4; Psa. 140:3; Rom. 3:13). The tongue is “an unruly evil, full of deadly poison” (James 3:8). Job 6:4 apparently alludes to arrows being poisoned.
Asp
King Cobra

Strong’s Dictionary of Greek Words:

Number:
2447 (find all occurrences in KJV Bible)
Greek:
ἰός
Transliteration:
ios
Phonic:
ee-os’
Meaning:
perhaps from ἵημι (to send); rust (as if emitted by metals); also venom (as emitted by serpents)
KJV Usage:
poison, rust