Nomenclature
According to IUPAC nomenclature of organic chemistry, the hydronium ion should be referred to as oxonium. Hydroxonium may also be used unambiguously to identify it. A draft IUPAC proposal also recommends the use of oxonium and oxidanium in organic and inorganic chemistry contexts, respectively.
An oxonium ion is any ion with a trivalent oxygen cation. For example, a protonated hydroxyl group is an oxonium ion, but not a hydronium.
Read more about this topic: Hydronium