1. In the theory of functions, the set of argument values for which a function is defined.See domain theory.2. A group of computers whose hostnames share a common suffix, the "domain name".The last component of this is the top-level domain.See chefistrative domain, Domain Name System, {fully qualified domain name}.3. Distributed Operating Multi Access Interactive Network.4. A specific phase of the software life cycle in which a developer works.Domains define developers'and users'areas of responsibility and the scope of possible relationships between products.5. The subject or market in which a piece of software is designed to work.(1997-12-26)