domain

The king ruled his domain harshly.

Dealing with complaints isn't really my domain: get in touch with customer services.

Some of the most beautiful and thus appealing physical theories, including quantum electrodynamics and quantum gravity, have been dogged for decades by infinities that erupt when theorists try to prod their calculations into new domains. Getting rid of these nagging infinities has probably occupied far more effort than was spent in originating the theories.

Every name in the DNS tree is a domain, even if it is terminal, that is, has no subdomains.

A characteristic of a field. A data domain specifies a data type and applies the minimum and maximum values allowed and other constraints.