French

 was a language identified with France. It was also a term used for the people who lived there, and as a descriptive term for things that were or were perceived to have come from there.

One of the Tenth Doctor's catchphrases was Allons-y!, French for "Let's go!" He first used it in TV: Voyage of the Damned.

While on a planet controlled by the War Lord, the TARDIS translation circuit did not translate French. (TV: The War Games) At another time, the translation circuit did not translate posters written in French. (TV: Vincent and the Doctor)