Definition of oxalic acid in US English:

oxalic acid


  • A poisonous crystalline acid with a sour taste, present in rhubarb leaves, wood sorrel, and other plants. Its uses include bleaching and cleansing.

    Alternative name: ethanedioic acid; chemical formula: (COOH)₂

    • ‘Then apply a solution of 4 ounces oxalic acid crystals dissolved in one gallon of warm water.’
    • ‘It is an excellent source of beta-carotene, vitamins C, E and K, calcium, potassium, iron, sodium, sulphur, folic acid and oxalic acid.’
    • ‘When it does so, however, it leads to the formation of highly toxic products - formic acid and oxalic acid, respectively.’
    • ‘Mix the ferric ammonium citrate and oxalic acid well, then add the silver nitrate.’
    • ‘Many cleaners are basically bleaches, containing bleaching agents, such as sodium hypochlorite or oxalic acid.’


Late 18th century: oxalic from French oxalique, via Latin from Greek oxalis ‘wood sorrel’.


oxalic acid

/ɑkˌsælɪk ˈæsəd//äkˌsalik ˈasəd/