pneum-

Partly from erroneous abbreviation of the fuller forms within English, and partly from the Koine and Byzantine Greek πνεῠμο- (pneumo-), a rare combining form of both the Ancient Greek πνεῠ́μων (pneumōn, "lung") and the Ancient Greek πνεῦμᾰ (pneuma, "air”, “wind”, “breath”, “spirit"); compare the French, German, and post-Classical Latin pneumo- ⁽ᶠʳ⁾ ⁽ᵈᵉ⁾ ⁽ˡᵃ⁾.