The Greek word barbaros originally described anyone who did not speak Greek — whose speech sounded like 'bar-bar' (incomprehensible babbling) to Greek ears. By the New Testament era it broadly referred to non-Greeks and non-Romans. Paul uses it in both neutral and gospel-expansive ways, declaring that in Christ there is neither Greek nor barbaros.
The use of barbaros in the New Testament dismantles cultural hierarchy. The ancient world divided humanity into civilized (Greek/Roman) and barbarian. Paul's declaration in Colossians 3:11 — 'there is no Greek or Jew, circumcised or uncircumcised, barbarian, Scythian, slave or free, but Christ is all' — is a radical gospel proclamation. The cross tears down every dividing wall between peoples.