Join Us On

Browse Dictionary Browse Thesaurus

Get our free apps!iPhone•iPad•Android

Medical Dictionary

hydronium

noun hy·dro·ni·um \hī-ˈdrō-nē-əm\

Medical Definition of HYDRONIUM

: a hydrated hydrogen ion H₃O⁺

What made you want to look up hydronium? Please tell us where you read or heard it (including the quote, if possible).

Put-downs with flair

How to use a word that (literally) drives some people nuts.

Test your vocab with our fun, fast game

Ailurophobia, and 9 other unusual fears

Join Us

Merriam-Webster
on Facebook

Merriam-Webster
on Twitter

Bookstore: Digital and Print

Merriam-Webster references for Mobile, Kindle, print, and more.

See All

Other Merriam-Webster Dictionaries