'antimonarchicalness' originates from Modern English, specifically formed from the prefix 'anti-' (from Greek 'anti' meaning 'against'), the root 'monarch' (from Greek 'monarkhēs' meaning 'sole ruler'), the adjectival suffix '-ical' (from Late Latin/French formation meaning 'relating to'), and the nominalizing suffix '-ness' (from Old English 'næs(s)e' meaning 'state or quality').

'antimonarchicalness' was built in Modern English by combining 'anti-' + 'monarch' + '-ical' + '-ness'. The element 'monarch' entered English via Late Latin/Old French from Greek 'monarkhia'/'monarkhēs', and English adjectival and nominal suffixes '-ical' and '-ness' were appended in the history of English word-formation to create the modern compound noun.

Initially the components meant 'against' (anti-), 'sole ruler' (monarch), and the affixes denoted 'relating to' and 'state/quality'; together they formed a coinage meaning 'the state or quality of being against monarchy', which has retained that compositional meaning in modern usage.