a field of action, thought, influence, etc.

the domain of science.

the territory governed by a single ruler or government; realm.

a realm or range of personal knowledge, responsibility, etc.

a region characterized by a specific feature, type of growth or wildlife, etc.

We entered the domain of the pine trees.

Law . land to which there is superior title and absolute ownership.

Mathematics .

the set of values assigned to the independent variables of a function.

region ( def. 11a ) .

Computers .

a group of computers and devices on a network that are administered under the same protocol.

the top level in a domain name, indicating the type of organization, geographical location, or both, and officially designated in the suffix, as .com for commercial enterprises in the U.S.

Physics . one of many regions of magnetic polarity within a ferromagnetic body, each consisting of a number of atoms having a common polarity, and collectively determining the magnetic properties of the body by their arrangement.

Crystallography . a connected region with uniform polarization in a twinned ferroelectric crystal.