Mathematics. ( 1 of a topology or topological space) having the property that every subset is an open set. 2  defined only for an isolated set of points: a discrete variable. 3  using only arithmetic and algebra; not involving calculus: discrete methods.
limestone - a sedimentary rock consisting mainly of calcium that was deposited by the remains of marine animals. atomic number 20, Ca, calcium - 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.
limestone is the name for a rock that is primarily composed of the mineral calcite distinguishing between rock and mineral terms is important though as a limestone rock may contain other minerals in addition to its calciteragonite aragonite is a polymorph of calcite a mineral that has the same chemical composition as calcite but has a slightly different crystal structure for most purposes aragonite and calcite can be considered to be the same mineral