any language used in a country other than one's own; a language that is studied mostly for cultural insight
Spanish has been present longer than English, but since the majority of the population are native speakers of English, Spanish is often termed a foreign language.
also foreign-language , (adj.)
Howard looked at me as if I were speaking a foreign language.
Murillo was born in Colombia and emigrated to London as a child, where he adopted a foreign language and cultural customs.
If only he'd known someone with a tattoo in a foreign language to tell him that its worth the trouble to get a translator.