'rabbi' originates from Hebrew, specifically the word 'רַבִּי (rabbi),' where 'רַב' meant 'master' or 'teacher'.

'רַבִּי (rabbi)' was adopted into Greek as 'ῥαββί (rhabbi),' and eventually became the modern English word 'rabbi'.

Initially, it meant 'master' or 'teacher' in a religious context, and this meaning has largely remained the same in modern usage.