oxalic acid

noun

ox·​al·​ic acid (ˌ)äk-ˈsa-lik- 

: a poisonous strong acid (COOH)₂ or H₂C₂O₄ that occurs in various plants (such as spinach) as oxalates and is used especially as a bleaching or cleaning agent and as a chemical intermediate

Examples of oxalic acid in a Sentence

Recent Examples on the Web

These involve removal of thorium from REE containing acidic solution, as well as the selective extraction of REEs using oxalic acid. —Aditya Jadhav, Interesting Engineering, 10 June 2026

Boiling tomatoes may reduce oxalic acid levels, which can help people prone to kidney stones, while increasing lycopene content. —Cristina Mutchler, Verywell Health, 10 June 2026

How To Clean Racks With Bar Keeper's Friend Bar Keeper's Friend's cleaning power comes from oxalic acid, an organic compound found in many fruits and vegetables. —Daley Quinn, Southern Living, 10 June 2026

Research had identified oxalic acid as a key factor in the blight’s virulence. —ArsTechnica, 12 Feb. 2026

Word History

Etymology

French (acide) oxalique, from Latin oxalis

First Known Use

1788, in the meaning defined above

Rhymes for oxalic acid

• antacid
• placid

Medical Definition

oxalic acid

noun

ox·​al·​ic acid (ˌ)äk-ˌsal-ik- 

: a poisonous strong acid (COOH)₂ or H₂C₂O₄ that occurs in various plants as oxalates and is used especially as a bleaching or cleaning agent and as a chemical intermediate