hydro- /haɪdrəʊ, -drə $ -droʊ, -drə/ AmE prefix
[ Language: Old French ; Origin: Latin , from Greek , from hydor 'water' ]
1 . relating to water, or using water:
hydroelectricity (=produced by water power)
hydrotherapy (=treatment of disease using water)
2 . relating to ↑ hydrogen , or containing it:
hydrocarbons