'eschatologist' originates from Greek via New Latin/Modern English, specifically from Greek 'eschatos' meaning 'last' and '-logia' (via Latin/Greek) meaning 'study', with the agent suffix '-ist' forming 'eschatologist'.

'eschatologist' developed from the noun 'eschatology' (Modern Latin/English), which itself comes from Greek 'eschatos' + '-logia'; the English word 'eschatology' entered scholarly use in the 17th–18th centuries, and 'eschatologist' was later formed by adding the English agent suffix '-ist'.

Initially built from elements meaning 'study of last things', the compound has retained that basic sense; over time it has come to refer both to academic specialists and to lay proponents of end-time beliefs.