'antre' originates from Old French, specifically the word 'antre', ultimately from Latin 'antrum' where 'antrum' meant 'cave'.

'antre' changed from Latin 'antrum' into Old French 'antre' and entered Middle English as 'antre', eventually surviving in modern English as the rare/archaic word 'antre'.

Initially, it meant 'cave' and over time it has retained that basic meaning but become chiefly archaic or literary in usage.