hydrogen ion

noun

1

: the cation H⁺ of acids consisting of a hydrogen atom whose electron has been transferred to the anion of the acid

2

: hydronium

Examples of hydrogen ion in a Sentence

Recent Examples on the Web

At the opposite surface, they are released as hydrogen ions again. — Rupendra Brahambhatt, Interesting Engineering, 26 Sep. 2026

Highly acidic foods donate hydrogen ions that react with and break down these long chain polymers called plastic. — Taylor Tobin, Southern Living, 5 Feb. 2026

Since the 1880s, human activities have increased the ocean’s concentration of acidic hydrogen ions by more than 26 percent. — Lauren Leffer, Popular Science, 27 Aug. 2025

Because of the angstrom-size pores in the material, the team discovered that UC-MAC was uniquely suited to turning molecular hydrogen ions into protons. — IEEE Spectrum, 18 Aug. 2025

Word History

First Known Use

1896, in the meaning defined at sense 1

Rhymes for hydrogen ion

• amphitryon
• dandelion
• herodian
• hawaiian
• ixion
• mauryan
• orion
• procyon
• visayan
• heian
• lion
• mayan

Kids Definition

hydrogen ion

noun

: the positive ion of acids that consists of a hydrogen atom whose electron has been transferred to the negative ion of the acid

Medical Definition

hydrogen ion

noun

1

: the cation H⁺ of acids consisting of a hydrogen atom whose electron has been transferred to the anion of the acid

2

: hydronium