Relating to hydraulics and pneumatics: see quots.

combining form of Greek ὑδραυλικός hydraulic, adj. n., as in hyˌdraulico-pneuˈmatical adj. Obsolete = hydraulo-pneumatical, adj. hyˌdraulicoˈstatics…

in same sense.

Pertaining to water and air or gas; applied to apparatus involving the combined action of water and air.