A commutative ring contained in a ring is said to be integrally closed in if every element of the integral closure of in is also in . That is, every monic polynomial with coefficients in has all of its roots in . Typically if one refers to a domain being integrally closed without reference to an overring, it is meant that the ring is integrally closed in its field of fractions.
If the ring is not a domain, typically being integrally closed means that every local ring is an integrally closed domain.
Sometimes a domain that is integrally closed is called "normal" if it is integrally closed and being thought of as a variety. In this respect, the normalization of a variety (or scheme) is simply the of the integral closure of all of the rings.
This property is somewhat stronger than the fact that an ordered group is Archimedean. Though for a lattice-ordered group to be integrally closed and to be Archimedean is equivalent. We have the surprising theorem that every integrally closed directed group is already abelian. This has to do with the fact that a directed group is embeddable into a complete lattice-ordered group if and only if it is integrally closed. Furthermore, every archimedean lattice-ordered group is abelian.