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: Webster's Revised Unabridged Dictionary (1913)