INTM153040 - Description of double taxation agreements: General definitions
These include
a) The United Kingdom
Great Britain and Northern Ireland and the continental shelf. The extension to the continental shelf is not included in some earlier agreements. It should be noted that as a matter of general law the Channel Islands and the Isle of Man do not form part of the United Kingdom and are therefore outside the scope of the territorial definition.
b) United Kingdom National
Any individual having the status of United Kingdom National (or, alternatively, any British citizen or any British subject not possessing the citizenship of any Commonwealth country or territory) provided that he or she has the right of abode in the United Kingdom and any legal person or other entity deriving its status as such from the law in force in the United Kingdom.
c) Person
An individual, a company and any other body of persons (see INTM163130 in relation to partnerships).
d) Company
Any body corporate, or any entity which is treated as a body corporate for tax purposes.
e) Enterprise of a contracting state
An enterprise carried on by a resident of a contracting state.
There is usually also a provision that any term not defined in the treaty will have the meaning that it has under the law of the relevant country for tax purposes.