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. Limestone is a sedimentary rock in the class known as chemical sedimentary rocks. It is composed chiefly of calcite, CaCO 3, and constitutes about 10 percent of all sedimentary rocks.Limestone may form inorganically or by biochemical processes.imestone. Limestone is a sedimentary rock in the class known as chemical sedimentary rocks. It is composed chiefly of calcite, CaCO 3, and constitutes about 10 percent of all sedimentary rocks.