'eschatological' originates from Modern Latin/Greek, specifically from Greek 'eschatologia' (ἐσχατολογία), where 'eschatos' meant 'last' and '-logia' meant 'study' or 'discourse'.

'eschatological' changed from the Greek word 'eschatologia' into Late/Medieval Latin 'eschatologia', entered theological Latin and then Middle English/Modern English as 'eschatology', with the adjective form 'eschatological' developing in English to describe relating to those studies.

Initially it meant 'pertaining to the study of last things' (a technical theological term), but over time it evolved to mean more generally 'relating to final events or ultimate destiny', including secular or metaphorical uses.