WordNet sense 1 (not belonging to that in which it is contained; introduced from an outside source):

extraneous

WordNet sense 2 (making impure or corrupt by adding extraneous materials):

adulterant, adulterating

WordNet sense 3 (not forming an essential part of a thing or arising or originating from the outside):

extrinsic

WordNet sense 4 (from or between other countries):

external, international, outside

WordNet sense 5 (in a foreign country):

overseas

WordNet sense 6 (being or coming from another country):

tramontane

WordNet sense 7 (being or from or characteristic of another place or part of the world):

alien, exotic

WordNet sense 8 (relating to or originating in or characteristic of another place or part of the world):

strange