External is used to indicate that something is on the outside of a surface or body, or that it exists, happens, or comes from outside.

External means involving or intended for foreign countries.

External means happening or existing in the world in general and affecting you in some way.

External experts, for example external examiners, come into an organization from outside in order to do a particular job fairly and impartially, or to check that a particular job was done properly.

If medicine is for external use, it is intended to be used only on the outside of your body, and not to be eaten or drunk.