'anti-royal' originates from the prefix 'anti-' (from Greek 'anti-', meaning 'against') combined with 'royal' (from Old French 'roial', from Latin 'regalis', meaning 'kingly').

'royal' changed from Old French 'roial'/'reial', borrowed from Latin 'regalis', and eventually became the modern English word 'royal'; 'anti-' entered English from Greek via Latin and Old French combining to form compounds like 'anti-royal'.

Initially the elements meant 'against' (anti-) and 'kingly' ('royal'); together they originally referred specifically to opposition to kings or the monarchy and have retained that central sense, now applied more broadly to opposition to royal institutions or sentiment.