Original Word: ἰός
Part of Speech: Noun, Masculine
Transliteration: ios
Pronunciation: ee-os'
Phonetic Spelling: (ee-os')
KJV: poison, rust
NASB: poison, rust
Word Origin: [perhaps from eimi "to go" or hiemi "to send"]

1. rust (as if emitted by metals)
2. venom (as emitted by serpents)

poison, rust.

Perhaps from eimi (to go) or hiemi (to send); rust (as if emitted by metals); also venom (as emitted by serpents) -- poison, rust.

Word Origin
a prim. word
Definition
rust, poison
NASB Translation
poison (2), rust (1).

STRONGS NT 2447: ἰός

ἰός, ἰοῦ, ὁ (on its very uncertain derivation see Kreussler in Passow, under the word; Curtius, § 591; (Vanicek, p. 969));

1. poison (of animals): ἰός ἀσπίδων ὑπό τά χείλη αὐτῶν, the poison of asps is under their lips, spoken of men given to reviling and calumniating and thereby injuring others, Romans 3:13 (from Psalm 139:3 ()); by the same figure, (γλῶσσα) μεστή ἰοῦ θανατηφόρου, James 3:8; (in Greek writings from Pindar down).

2. rust: James 5:3; (Ezekiel 24:6, 11f; Baruch 6:11, 23 (Epistle Jeremiah 12, 24); Theognis, Theocritus, Plato, Theophrastus, Polybius, Lucian, others).

Greek Term and Semantic Field

Strong’s Greek 2447 (ἰός, ios) gathers two seemingly disparate ideas—“poison” and “corrosion.” Whether describing the toxic secretion of serpents or the rust that eats away at metal, the term uniformly portrays an invisible but relentless agent of death and decay. Scripture employs this imagery to expose the devastating power of sin in speech, wealth, and the human heart.

Biblical Occurrences

1. Romans 3:13 – “The venom of vipers is on their lips.”
2. James 3:8 – “It is a restless evil, full of deadly poison.”
3. James 5:3 – “Your gold and silver are corroded. Their corrosion will testify against you and consume your flesh like fire.”

These three texts span two writers (Paul and James) and three topics—deceitful speech, untamed tongues, and hoarded wealth—yet converge on a single warning: unchecked sin works like ἰός, silently corrupting until ruin becomes manifest.

Historical–Cultural Background

In the Greco-Roman world, rust symbolized inevitable decay. Although precious metals do not oxidize like iron, they can tarnish or be reduced to worthlessness through confiscation or market collapse. Ancient people also feared serpent venom, often fatal without remedy. Both realities provided apt metaphors for moral corruption: wealth and words may appear harmless, yet under sin’s influence they become agents of destruction.

Theological Significance

• Radical Depravity: Romans 3:13 anchors Paul’s indictment of universal sinfulness (Romans 3:9-18). Venom on human lips pictures mankind’s fallen nature, confirming the need for the righteousness that comes “apart from the law” (Romans 3:21).
• Ethical Integrity: James 3:8 confronts believers with the tongue’s lethal potential, urging pursuit of heavenly wisdom (James 3:17) empowered by the Spirit (Galatians 5:22-23).
• Eschatological Accountability: James 5:3 portrays corroded riches rising as courtroom witnesses on the Day of the Lord. Corrosion is not merely chemical; it is moral evidence that wealth was hoarded rather than deployed for kingdom purposes.

Connections within Scripture

Old Testament precursors mirror both senses of ἰός: Deuteronomy 32:33 laments “the venom of serpents,” while Ezekiel 24:6 depicts the “rust” (ḥel’â) of a boiling pot—imagery later echoed by James. Isaiah 1:22’s “dross” and Psalm 140:3’s “poison of vipers” converge to foreshadow the New Testament usage. In each context, God exposes internal impurity that only He can purge (Isaiah 1:25).

Christological Implications

The gospel addresses every facet of ἰός:
• Christ endured the world’s venom—verbal slander, betrayal, and the malice of rulers—yet “no deceit was found in His mouth” (1 Peter 2:22).
• On the cross He became “sin for us” (2 Corinthians 5:21), absorbing the poison so that believers might receive the antidote of His righteousness.
• His resurrection assures a future where neither rust nor decay can touch the believer’s inheritance (1 Peter 1:4).

Practical Applications

1. Speech: Guard the tongue through Scripture meditation and prayer; what fills the heart will flavor the lips (Luke 6:45).
2. Wealth: Convert perishable riches into eternal currency by generosity (1 Timothy 6:17-19).
3. Holiness: Recognize subtle corruption early; repentance is easier before poison spreads (Hebrews 3:13).

Pastoral Reflections

Ἰός teaches that sin’s most potent work is often silent. Like rust beneath a polished surface or venom coursing unseen through veins, moral decay hides until calamity erupts. Yet the same Lord who exposes ἰός also provides the remedy: the cleansing word (John 15:3), the purifying blood (1 John 1:7), and the incorruptible hope of glory (Colossians 1:27).

ιος ιός ἰὸς ιου ιού ἰοῦ ιούς ios iòs iou ioûInterlinear Greek • Interlinear Hebrew • Strong's Numbers • Englishman's Greek Concordance • Englishman's Hebrew Concordance • Parallel Texts