'antidisestablishmentarianism' originates from English components: the prefix 'anti-' (from Greek 'anti' meaning 'against'), the prefix 'dis-' (from Latin 'dis-' meaning 'apart, not'), the noun 'establishment' (from 'establish', from Old French/Latin roots meaning 'to set up or make firm'), the agentive/adjectival suffix '-arian' (from Latin '-arius'), and the noun-forming suffix '-ism' (from Greek '-ismos' / Latin '-ismus').

'antidisestablishmentarianism' was formed in 19th-century Britain during debates about the proposed disestablishment of the Church of England; it derived from the phrase 'anti-disestablishment' + the agentive '-arian' and nominalizing '-ism', producing the modern compound 'antidisestablishmentarianism'.

Initially, it specifically referred to opposition to proposals to disestablish (remove official status from) a state church (notably the Church of England); over time, in addition to that political meaning it has become well known as an example of a very long English word and is frequently used jokingly or pedagogically for its length.