καίω
I ignite, light, burn
Definition
The verb καίω means 'to burn' or 'to be on fire,' used both literally and metaphorically. Literally, it describes the physical act of burning a lamp (Matthew 5:15) or a bush (Hebrews 12:18). Metaphorically, it expresses the intense, consuming nature of spiritual realities: the heart can 'burn' with spiritual recognition (Luke 24:32), a person can be a 'burning' lamp of witness (John 5:35), and unfruitful branches are thrown into the fire to be 'burned' (John 15:6). It also denotes the act of being consumed by fire, as in sacrificial burning (1 Corinthians 13:3).
Biblical Usage
Used 12 times in the New Testament, καίω appears in Gospels, epistles, and Revelation. In the Gospels, it often illustrates spiritual readiness or testimony (Luke 12:35, John 5:35). Paul uses it once to emphasize the worthlessness of sacrifice without love (1 Corinthians 13:3). In Revelation, it describes the heavenly throne's torches (Revelation 4:5). The pattern shows a balance between concrete imagery (lamps, fire) and powerful metaphors for spiritual passion or judgment.
Etymology
Derived from the Proto-Indo-European root *keh₂u-, meaning 'to burn' or 'to heat.' It is a primary verb in Greek, giving rise to related words like καῦμα (kauma, G2738) for 'heat' and καῦσις (kausis, G2740) for 'burning.' Its meaning remained stable, centered on the concept of combustion.
Semantic Range
This word is theologically significant for illustrating divine presence, judgment, and spiritual fervor. The 'burning' heart in Luke 24:32 signifies the inner witness of Christ through Scripture. In John 15:6, burning represents the final judgment for those not abiding in Christ. The imagery connects God's revealing light (John 5:35) with His consuming holiness (Hebrews 12:18, Revelation 4:5), enriching our understanding of both God's illuminating grace and righteous judgment.
In the 1st-century world, controlled fire from lamps or torches was essential for light and safety after dark, making the image of a 'burning' lamp (Matthew 5:15) a powerful symbol of preparedness and visibility. Fire was also a primary means of disposal and sacrifice, so the metaphor of burning branches (John 15:6) would be immediately understood as complete destruction or purification.
πυρόω (pyroō, G4448) — to set on fire, often with a focus on the process of igniting or refining; φλέγω (phlegō, G5394) — to blaze, burn fiercely, used in Revelation for eternal fire.
Word Details
How this works
Definitions are from the Dodson Greek-English Lexicon, a concise public-domain resource suitable for introductory word study. Brief glosses are supplemented by STEPBible TBESG data (CC BY 4.0). For advanced research, standard scholarly references include BDAG (Danker, 3rd ed.) and LSJ.
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