'medievalist' originates from Modern English, specifically the word 'medieval' with the suffix '-ist', where 'medieval' meant 'relating to the Middle Ages'.

'medieval' came into English from Old French 'médiéval', ultimately from Medieval Latin 'mediaevalis' (from Latin 'medius' meaning 'middle' + 'aevum' meaning 'age'); the modern English noun 'medievalist' was formed by adding the agentive suffix '-ist' to 'medieval'.

Initially, related forms meant 'pertaining to the Middle Ages'; over time the derived noun came to mean 'a specialist or scholar of the Middle Ages'.