The Collaborative International Dictionary
Pneumato-
Pneumato- \Pneu"ma*to-\ (n[=u]"m[.a]*t[-o]- or n[-u]*m[a^]t"[-o]-). A combining form from Gr. pney^ma, pney`matos, wind, air, breath, respiration; as, pneumatograph, pneumatology.
Douglas Harper's Etymology Dictionary
pneumato-
before vowels pneumat-, word-forming element meaning "wind, air, spirit, presence of air," from comb. form of Greek pneuma (genitive pneumatos); see pneuma.
Wiktionary
pneumato-
pre. '''pneumat-''' + '''-o-'''