'anti-monarchism' is a compound formed in English from the prefix 'anti-' plus 'monarchism'. 'anti-' originates from Greek 'anti' meaning 'against', and 'monarchism' comes from 'monarch' + the suffix '-ism'.

'monarch' originates from Greek 'monárkhēs' (from 'mónos' meaning 'single' and 'arkhê' meaning 'rule'), passed into Latin and Old French (e.g. 'monarque'), and into Middle English as 'monarch'. The suffix '-ism' (from Greek -ismos via Latin/French) created 'monarchism' to denote the doctrine or support of monarchy; 'anti-' attached as a productive English prefix produced 'anti-monarchism' in modern political usage.

The compound originally and consistently meant 'opposition to monarchy'; over time its usage broadened to include formal political movements, ideological positions, and general anti-royal sentiments.