'tallier' originates from English, formed from the verb 'tally' plus the agent suffix '-er'; 'tally' ultimately comes from Anglo-Norman/Old French 'tallie' (from Medieval Latin 'talea'), where '-er' meant 'one who performs an action'.

'talea' in Medieval Latin developed into Old French/Anglo-Norman 'taille'/'tallie', which entered Middle English as 'tally'; adding the agentive suffix '-er' produced 'tallier', and its regular plural became 'talliers'.

Initially, it meant 'one who keeps a tally (marks on a stick for accounts)', and it broadened to 'one who counts or records totals, especially votes or items'.