Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “hydronium”


noun [U]    /hɑɪˈdroʊ·ni·əm/
chemistry an ion of hydrogen that has been combined with water
(Definition of hydronium noun from the Cambridge Academic Content Dictionary © Cambridge University Press)
Focus on the pronunciation of hydronium

Word of the Day


an ability to do things in the stated, especially positive, way

Word of the Day


Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More