phosphonic acid

 
Pronunciation: /fɒsˈfɒnɪk/

noun

[mass noun] Chemistry
  • a crystalline acid obtained by the reaction of phosphorus trioxide with water.
    • A dibasic acid; chemical formula: HPO(OH)2

Origin:

late 19th century: phosphonic from phospho- 'relating to phosphorus', on the pattern of sulphonic