Meaning

noun a nonmetallic univalent element that is normally a colorless and odorless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe

originEtymology tree Proto-Indo-European *wed- Proto-Indo-European *-r̥ Proto-Indo-European *wódr̥ Proto-Hellenic *údōr Ancient Greek ῡ̆̔́δωρ (hū̆́dōr) Ancient Greek ὑδρο- (hudro-)lbor. French hydro- Proto-Indo-European *ǵenh₁- Proto-Indo-European *-os Proto-Indo-European *ǵénh₁os Proto-Hellenic *génos Ancient Greek γένος (génos) Proto-Indo-European *-os Proto-Indo-European *-ēs Ancient Greek -ης (-ēs)…

Etymology from Wiktionary, CC BY-SA 3.0