language (n.) Look up language at
late 13c., langage "words, what is said, conversation, talk," from Old French langage "speech, words, oratory; a tribe, people, nation" (12c.), from Vulgar Latin *linguaticum, from Latin lingua "tongue," also "speech, language," from PIE *dnghu- "tongue" (see tongue (n.)).

The -u- is an Anglo-French insertion (see gu-); it was not originally pronounced. Meaning "manner of expression" (vulgar language, etc.) is from c. 1300. Meaning "a language," as English, French, Arabic, etc., is from c. 1300; Century Dictionary" defines this as: "The whole body of uttered signs employed and understood by a given community as expressions of its thoughts; the aggregate of words, and of methods of their combination into sentences, used in a community for communication and record and for carrying on the processes of thought." In Middle English the word also was used of dialects:
Mercii, þat beeþ men of myddel Engelond[,] vnderstondeþ bettre þe side langages, norþerne and souþerne, þan norþerne and souþerne vnderstondeþ eiþer oþer. [John of Trevisa, translation of Bartholomew de Glanville's "De proprietatibus rerum," 1398]

In oþir inglis was it drawin, And turnid ic haue it til ur awin Language of the norþin lede, Þat can na noþir inglis rede. ["Cursor Mundi," early 14c.]
Language barrier attested from 1885.