9 letters · 18 points in Scrabble
originEtymology tree Proto-Indo-European *wed- Proto-Indo-European *-r̥ Proto-Indo-European *wódr̥ Proto-Hellenic *údōr Ancient Greek ῡ̆̔́δωρ (hū̆́dōr) Ancient Greek ῠ̔δρο- (hŭdro-)der. English hydro- New Latin ammōniumbor. English ammonium English onium English hydronium From hydro- + onium.
Etymology from Wiktionary, CC BY-SA 3.0