D defs.my
Entry 1 sense Webster, 1913

Phosphonic

/(fŏs*fŏn"ĭk)/ · Phos·phon·ic · IPA
01 a. Pertaining to, or designating, certain derivatives of phosphorous acid containing a hydrocarbon radical with the phosphorus directly bonded…
  1. 1.
    Pertaining to, or designating, certain derivatives of phosphorous acid containing a hydrocarbon radical with the phosphorus directly bonded to a carbon, and analogous to the sulphonic acids; as, methanephosphonic acid, CH3.PO.(OH)2.(Chem.)