A note on this entry
πνεῦμα is not a headword in any of the three great etymological dictionaries. Beekes, Chantraine, and Frisk all treat it where it belongs — as a derivative inside the article on the verb πνέω "to blow, breathe" (Beekes, EDG s.v. πνέω, #5069; Chantraine, DELG s.v. πνέω, #6632; Frisk, GEW s.v. πνέω, #4729). The entry below is therefore built on the πνέω article and the corpus record, and it is honest about the seam: a Logoi article exists for every indexed lemma, but the etymology of πνεῦμα is the etymology of πνέω.
The derivation
πνεῦμα is a -μα noun built on πνέω — the resultant-noun of the verb of breathing, exactly as θέμα stands to τίθημι. The interest is twofold.
The verb is onomatopoeic. Chantraine is explicit: πνέω "doit appartenir à une famille de nuance expressive qui peut plus ou moins reposer sur des onomatopées" — it belongs to an expressive family that more or less rests on onomatopoeia, the sound of blowing and snorting itself. The Germanic cognates are wonderfully concrete: Old Norse fnýsa "to snort, blow noisily," Old English fnēosan "to sneeze" (Chantraine, citing Pokorny 838; Beekes reconstructs the root *pneu- "breathe, cough, smell"). The Greek word for spirit begins in the noise of a sneeze.
The breath-soul pattern, again. This is where πνεῦμα joins the deepest current in the soul-vocabulary. In the article on ψυχή, both Frisk and Beekes invoke πνεῦμα : πνέω as the model for ψυχή : ψύχω — soul-from-breathing — alongside Latin animus/anima from the root of Sanskrit aniti "to breathe." Greek had two verbs for "breathe," ψύχω and πνέω; ψύχω drifted toward "cool, blow," and πνέω won — "das sich gegen ψύχω siegreich behauptet hat," in Frisk's phrase. πνεῦμα is the noun of the verb that won. Where ψυχή became the breath that departs (the shade), πνεῦμα remained the breath that moves — wind, respiration, and finally spirit.
Root
- *pneu- "to breathe, blow" (Beekes, s.v. πνέω) — an expressive/onomatopoeic root, cognates chiefly Germanic (fnýsa, fnēosan). πνεῦμα the -μα derivative; no separate root of its own. Compare the parallel breath-soul derivations under ψυχή.
In the corpus
83 occurrences — and not one in Homer. This is the diagnostic fact: πνεῦμα is absent from the Iliad and Odyssey entirely, surfacing only with the philosophers — Plotinus's Enneads (27) and Plato's Timaeus (23) lead, with Aristotle, the Stoics (Epictetus, Marcus), and the medical treatises following. πνεῦμα is a later soul-word, the breath that philosophy and medicine raised to a technical term — the Stoic πνεῦμα that pervades the cosmos, and the πνεῦμα that the Septuagint and New Testament would make the Holy Spirit (a development Chantraine's article explicitly flags: "dans le NT l'Esprit Saint"). Where θυμός ruled Homer and faded, πνεῦμα was nearly absent from Homer and rose.
The word's world
πνεῦμα carries the breath-soul idea out of the body and into the cosmos. The interpretive record returned from the Oracle situates it in the Stoic system, where breath becomes the active principle running through all matter — pneuma as the tension (τόνος) that holds bodies together and the medium of cause itself (The Hellenistic Philosophers; Stoicism and Emotion). The same word that began as the snort of πνέω becomes, by the Stoics and after, the spirit that animates the world — and the cleanest illustration in this pilot of a soul-word's whole arc: from onomatopoeia, to wind, to breath, to Spirit.
Authorities: πνεῦμα is treated s.v. πνέω in all three — Beekes, Etymological Dictionary of Greek (Brill 2010) s.v. πνέω (scan pp. 1264–1265, #5069); Chantraine, Dictionnaire étymologique de la langue grecque s.v. πνέω (scan p. 937, #6632); Frisk, Griechisches etymologisches Wörterbuch s.v. πνέω (scan pp. 1538–1539, #4729–4730). Interpretive sources retrieved from the Oracle library (Classical Philology & Ancient Thought): The Hellenistic Philosophers (Long & Sedley, 1987); Stoicism and Emotion (2007). Cognate / root references: Pokorny 838; Mayrhofer. Corpus figures: Logoi corpus, live. Receipt: soul-word-journey-v0.