- calcium, Ca, atomic number 20 - a white metallic element that burns with a brilliant light; the fifth most abundant element in the earth's crust; an important component of most plants and animals
--1 is a kind of metallic element, metal
--1 is a substance of
--1 has particulars: calcium ion, factor IVcalcium oxide, quicklime, lime, calx, calcined lime, fluxing lime, unslaked lime, burnt lime; limestone; gypsum; fluorite, fluorspar, fluor Derived forms: verb calcify1, verb calcify4, verb calcify3