bicarbonate UK /baɪˈkɑː.bə.nət/US /baɪˈkɑɹ.bə.neɪt/ noun2 •the univalent anion HCO₃⁻; any salt of carbonic acid in which only one of the hydrogen atoms has been replaced. •Clipping of sodium bicarbonate, especially that used as a mild antacid. formsbicarbonates