'amillennialist' originates from Modern English, specifically formed from the Greek prefix 'a-' meaning 'not', the Late Latin word 'millennium' meaning 'a thousand years', and the suffix '-ist' meaning 'one who holds a belief'.

'amillennialist' developed from the adjective 'amillennial' + the agentive suffix '-ist'. 'Millennium' itself comes from Latin 'mille' ('thousand') + 'annus' ('year'), passed into Late Latin as 'millennium' and then into English; the negating prefix 'a-' (from Greek) was attached in modern theological usage to form 'amillennial', later producing 'amillennialist'.

Initially, 'millennium' meant 'a thousand-year period'; over time 'amillennialist' came to mean specifically 'a person who denies or interprets non-literally the idea of a literal 1000-year earthly reign of Christ'.