hydro- A prefix that means: “water” (as in hydroelectric) or “hydrogen,” (as in hydrochloride).

What does Hydro refer to?

hydro- A prefix that means: “water” (as in hydroelectric) or “hydrogen,” (as in hydrochloride).

Why hydro means water?

before vowels hydr-, word-forming element in compounds of Greek origin, meaning "water," from Greek hydro-, combining form of hydor "water" (from suffixed form of PIE root *wed- (1) "water; wet"). Also sometimes a combining form of hydrogen.