[hydr-] or hydro- comb form [ME ydr-, ydro-, fr. OF, fr. L hydr-, hydro-, fr. Gk, fr. hydor--more at water] 1 a: water "hydrous" "hydroelectric" b: liquid "hydrokinetic"
2: hydrogen: containing or combined with hydrogen "hydrocarbon" "hydroxyl"
3: hydroid "hydromedusa"