'ultra-monarchist' originates from a compound of the prefix 'ultra-' and the noun 'monarchist'. 'ultra-' ultimately comes from Latin 'ultrā', where 'ultra' meant 'beyond' or 'on the other side', and 'monarchist' derives from Greek 'monárkhēs' (via Latin/Old French), where 'monos' meant 'single' or 'alone' and 'arkhē/arch-' meant 'rule'.

'ultra-monarchist' developed in modern English by compounding 'ultra-' with 'monarchist'. The political use of 'ultra' in labels (e.g. French 'ultra-royaliste' / English 'ultra-royalist') in the 19th century helped form related English compounds; 'monarchist' entered English via medieval borrowings from Latin/Old French based on the Greek 'monárkhēs'.

Initially, 'ultra' meant 'beyond' and 'monarchist' simply meant 'supporter of monarchy'; combined, 'ultra-monarchist' came to mean 'one who supports monarchy to an extreme degree', a political label that emphasizes uncompromising royalist positions.