from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Having two hydrogen ions to donate to bases in an acid-base reaction.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Tending to donate two hydrogen ions (H+) in solution.
HNO3 = monoprotic acid H2SO4 = diprotic acid H3PO4 = triprotic acid HC2H3O2 = monoprotic protic aka proton