äkˈsōnēəm noun
( -s )
Etymology: New Latin, from ox- (I) + -onium
: the univalent cation H 3 O + derived from oxygen and known especially in the form of organic derivatives : the monohydrated hydrogen ion
diethyl- oxoium chloride [(C 2 H 5 ) 2 HO] + Cl -
— called also hydronium