E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
is certainly not derived from the Latin barba (a beard), as many suppose, because it is a Greek word, and has many analogous ones. The Greeks and Romans called all foreigners barbarians (babblers; men who spoke a language not understood by them); the Jews called them Gentiles (other nations); the Russians Ostiaks (foreigners). The reproachful meaning crept in from the natural egotism of man. It is not very long ago that an Englishman looked with disdainful pity on a foreigner, and the French still retain much of the same national exclusiveness. (See WUNDERBERG.)
If then I know not the meaning of the voice [words], I shall be to him that speaketh a barbarian [a foreigner], and he that speaketh will be a barbarian unto me.1 Cor. xiv. 11.