ἰός

iós

G2447 noun

SILEX Entry

Definition

Primarily, a harmful or toxic substance; specifically, poison or venom, especially as produced by serpents or other animals. In other contexts, refers to corrosive substance such as rust, particularly the decay or corruption that spreads and destroys. Figuratively, the word can denote moral corruption, dangerous influence, or a destructive agent.

Semantic Range

poisonous substance, venom (of snakes), rust (corrosion of metals), moral or spiritual corruption, destructive influence

Root / Etymology

The etymology is uncertain. Though the Strong's gloss speculates a relationship to verbs such as 'to go' (εἶμι) or 'to send' (ἵημι), no clear linguistic derivation has been established. The word is attested independently in Greek literature as a noun for poisonous or corrosive substances.

Historical & Contextual Notes

In classical Greek, ἰός was most commonly used to signify 'arrow,' but in the sense relevant to New Testament and Septuagint usage (and as attested in later Greek, including Koine), the meaning shifts to 'poison' or 'venom,' particularly that produced by animals like serpents. In the Septuagint and New Testament, ἰός can refer metaphorically to harmful speech or influence (e.g., 'the poison of asps is under their lips' in Romans 3:13, echoing Psalm 140:3 LXX). When used to mean 'rust' or a corrosive substance, it metaphorically highlights destruction from within, as in James 5:3 where 'your gold and silver have rusted (ὁ ἰὸς αὐτῶν)' signifies moral decay due to greed. English translations often choose 'poison' or 'venom' in animal or moral imagery contexts, and 'rust' in material decay; however, these do not always capture the term's interconnected imagery of corruption and destruction, whether biological or moral. The semantic range in Koine overlaps with but is narrower than the earlier arrow/shaft sense, which disappears from later contexts. The figurative moral sense gains prominence in Jewish-Greek writings and the New Testament.

Original Strong's Gloss (1890)

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

Root Family

ἰός (ios) — poison, venom, rust, corrosive substance

Root ἰός poison, venom, rust, corrosive substance

Word Forms

2 distinct forms

SIDANCE Surface Transliteration Morphology Common SIBI-P1 SIBI-P2 Occurrences
G2447-01 ἰὸς ios N NOM M SG poison poison poison 2
G2447-02 ἰοῦ iou N GEN M SG of poison of poison of poison 1

Occurrences in Scripture

3 occurrences

SIDANCE Reference Word Transliteration Morphology Common SIBI-P1 SIBI-P2
G2447-01 Romans 3:13 ἰὸς ios N NOM M SG poison poison poison
G2447-02 James 3:8 ἰοῦ iou N GEN M SG of poison of poison of poison
G2447-01 James 5:3 ἰὸς ios N NOM M SG rust poison rust