Ancient Greek has two words that are translated as life in English: zōē and bios. What is the difference between them? What are their cognates in other Indo-European languages?

  • @jknappen: the Help center says we should welcome questions about "any natural language from a linguistics point of view... a single word in relation to multiple languages or a single word/single language." This question asks about the etymology of two single words and their cognates. It also asks about the difference in meaning; perhaps that part is not so much in the scope of this site. But for the most part, isn't this a question about historical linguistics? Commented Feb 15, 2016 at 19:26
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    I'd love to see a good answer myself, besides what I can find in Montanari, bios "life of a human; lifespan; biography" vs. zoe "life."
    – Alex B.
    Commented Feb 16, 2016 at 3:39
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    The meaning of individual non-function words is definitely off-topic. If you need recommendations for a good dictionary we can probably help though.
    – curiousdannii
    Commented Feb 16, 2016 at 12:37
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    C.S. Lewis's Studies in Words has a great chapter on "life" across languages, including ancient Greek. Commented Jan 19, 2018 at 13:16
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    These questions now belong to Latin SE, which also accepts Ancient Greek. Commented Aug 5, 2021 at 11:59

5 Answers 5


These two words are actually cognate with each other; they show the differing reflexes in Greek of labiovelar consonants. In the noun ζωή zōē and the corresponding adjective ζωός zōos, the initial ζ developed from a cluster with the semivowel y; the noun βίος bios shows the normal development of PIE *gʷ before the full vowel /i/.

The Online Etymology Dictionary's entry for the (English) prefix bio- also lists an assortment of cognates in other branches of Indo-European:

Sanskrit jivah "alive, living;" Old Persian *jivaka- "alive," Middle Persian zhiwak "alive;" Old English cwic, cwicu "living, alive;" Latin vivus "living, alive," vita "life;" Old Church Slavonic zivo "to live;" Lithuanian gyvas "living, alive," gyvata "(eternal) life;" Old Irish bethu "life," bith "age;" Welsh byd "world")

It also has the following note on the meaning:

The correct usage is that in biography, but in modern science it has been extended to mean "organic life."

This is supported by the definition of βίος in Henry George Liddell and Robert Scott's A Greek-English Lexicon, edited by Sir Henry Stuart Jones:

life, i. e. not animal life (ζωή), but mode of life

(accessed from the Perseus Digital Library on 15 February 2016)

Wiktionary describes the noun ζωή as a derivative of the verb ζάω, ζώω (meaning "to live"), and gives the verb's etymology as follows:

From Proto-Hellenic *ǰṓw-ō, from *gʷyṓw-ō, from Proto-Indo-European *gʷíh3w-oh2.

In Attic Greek inherited /w/ was lost.

Piotr Gąsiorowski explains in the comments here how βίος and ζωός developed from the same Proto-Indo-European root:

*gʷih₃w-ó- ‘living’ and *gʷíh₃w-e/o- ‘to live’. The change *-ih₃- > *-jō is an inner Greek development (parallelled by similar changes in Tocharian and Armenian). It’s known as Francis–Normier’s law, or laryngeal breaking. Not everybody accepts it, but they really should. The ‘life’ root alone would be evidence enough for it. [...]

The Greek development of the inherited labiovelars is complex and differs from dialect to dialect, but the normal (expected) Attic reflex of *gʷ before *i and *ī is b, not d (though *gʷj yields z). Therefore, both βίος and ζωός are regular.


Regarding their meaning/usage during the "Classical" and "Hellenistic" period in non-technical literature, I would say ζωή refers the opposite of "death" in terms of existence, and is used for animals, plants, etc., with common overtones of transcendence, whereas βίος refers to human lifestyles and activities, which by metonymy would also relate to things need to sustain such "life."


In Christian theology the usage of the original greek words in the bible give way to the churches to interpret the message for congeragation members. FE. Jesus said he is the way, the truth and the life (ζάω). In this case ζωή differs from bios. ζωή refers to 1 to live, breathe, be among the living (not lifeless, not dead). 2 to enjoy real life. 2a to have true life and worthy of the name. 2b active, blessed, endless in the kingdom of God. Bios refers to just life as opposed to not being alive.


A partial answer regarding the meaning: Ivan Illich writes in the essay "The Institutional Construction of a New Fetish: Human Life" published in the book "In The Mirror of the Past":

"The concept of life does not exist in Greco-Roman antiquity: bios means the course of a destiny and zōē something close to the brilliance of aliveness. In Hebrew, the concept is utterly theo-centric, an implication of god`s breath."


C.S. Lewis in Mere Christianity uses the word Bios to denote biological life and Zoe spiritual life:

The Biological sort which comes to us through Nature, and which (like everything else in Nature) is always tending to run down and decay so that it can only be kept up by incessant subsidies from Nature in the form of air, water, food, etc., is Bios. The Spiritual life which is in God from all eternity, and which made the whole natural universe, is Zoe.

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