barbaro

Nothing to do with beards. Barbo is a beard, sitting at rank 1,489, and barbaro looks like barb- plus -ar-, the collective suffix - a collection of beards, which for an unwashed horde is such a satisfying reading that people have been known to defend it. It is a false seam. Barbar- is one Greek root and barb- is a separate Latin one, and the resemblance is pure accident of sound. It is worth checking your instinct here precisely because the wrong answer is so much more fun than the right one.

The right answer is better anyway. The Greeks heard foreign speech as bar bar bar - meaningless syllables - and made a word out of the mockery. So a barbaro began as nothing more than a person who does not speak your language, which is exactly the sense the second example above preserves. Rome took the word and pointed it at everyone outside the empire; the sense of cruelty and destruction is the third layer, added by centuries of people who had been on the wrong end of an invasion. A word that started as a joke about accents ended as an accusation of savagery.

How to use it now. Barbaro is the person, barbara the adjective, barbareco the quality and barbaraĵo a barbarous act. All four are current, all four are strong, and all four are worth using carefully: the word carries the whole history of one people deciding another was not fully civilised because of how they sounded. The neutral alternatives are fremdulo for a stranger and eksterlandano for a foreigner. Note also the odd echo in barbarismo, which in grammar means a foreign or malformed word - the original linguistic sense, still doing its old job.