'anti-Arab' originates from English as a compound of the prefix 'anti-' and the noun 'Arab'; 'anti-' ultimately comes from Greek 'anti' meaning 'against', and 'Arab' comes from Arabic 'Arab' (via Greek/Latin).

'anti-' entered English via Latin and Old French from Greek 'anti'; 'Arab' entered English via Medieval Latin/Old French from Arabic 'Arab'; the compound 'anti-Arab' developed in modern English to denote opposition or hostility toward Arabs.

Initially it literally meant 'against Arabs' (a simple descriptive compound), but over time it has become used primarily to describe prejudice, hostility, discrimination, or political opposition directed at Arabs.