Source : Webster's Revised Unabridged Dictionary (1913)

Bicarbonate \Bi*car"bon*ate\, n. [Pref. bi- + carbonate.]
   (Chem.)
   A carbonate in which but half the hydrogen of the acid is
   replaced by a positive element or radical, thus making the
   proportion of the acid to the positive or basic portion twice
   what it is in the normal carbonates; an acid carbonate; --
   sometimes called {supercarbonate}.

Source : WordNet®

bicarbonate
     n : a salt of carbonic acid (containing the anion HCO3) in which
         one hydrogen atom has been replaced; an acid carbonate
         [syn: {hydrogen carbonate}]