Main Entry: ¹re·serve

Pronunciation: \ri-ˈzərv\

Function: noun

1 : something stored or kept available for future use or need <oxygen reserve>—see cardiac reserve
2 : the capacity of a solution to neutralize alkali or acid when its reaction is shifted from one hydrogen-ion concentration to another ; especially : the capacity of blood or bacteriological media to react with acid or alkali within predetermined and usually physiological limits of hydrogen-ion concentration—compare buffer, buffer solution