In Ancient Greece, the name βάρβαρος, bárbaros, was given to all those who did not speak the Greek language. Later, the term Barbarian came to mean 'Anyone who is not Greek'. Later again, it meant 'anyone who is outside the Roman Empire'.
It is used for a member of a nation or ethnic group which is seen as having a lower level of civilization, or for an individual person which is seen as a brutal, cruel and insensitive or whose behaviour is unacceptable in the civilized society of the speaker. When used for a person the word is always pejorative, when used for a nation not always.