The words 'barbarian' or 'barbaric' as we use them today, have evolved far from their ancient Greek and Roman origins into words with far more negative connotations than their original meanings. Today, 'barbaric' is most often used to describe something brutal, savage or uncivilised, whilst a 'barbarian' is someone who displays these characteristics.
'Barbarian' is derived from the ancient Greek word 'bárbaros', meaning babbler, and was used to describe people from non-Greek speaking countries such as Persia and Egypt, who, to Greek ears, sounded like they were make unintelligible sounds (ba-ba-ba). Other similar words also exist in European languages such as the Sanskrit 'barbara' which means to stammer.
The Romans were the first people to add the negativity to the word, using 'barbarian' to describe any foreigners, including tribes, who didn't follow Roman traditions. The word evolved into common use by historians and scholars when describing attacks on larger civilisations by enemies who weren't part of their traditions.