'antiforeign' is formed from the Greek prefix 'anti-' meaning 'against' combined with English 'foreign', which ultimately comes from Old French 'forain' (meaning 'from outside').

'foreign' developed from Old French 'forain' (from Latin 'foraneus') and Middle English forms such as 'forain, forene' into modern English 'foreign'; 'anti-' comes from Greek 'anti-' and has been used in English since the classical/early modern periods to form compounds meaning 'against'.

Initially the components meant 'against' (anti-) and 'from outside' (foreign); together they now denote opposition to foreigners or foreign influence (a modern compound sense of opposition to outsiders).