'doornail' originates from Old English, specifically the words 'duru' and 'nægel', where 'duru' meant 'door' and 'nægel' meant 'nail'.

'doornail' changed from Middle English forms such as 'dornail' or 'dornayl' and eventually became the modern English word 'doornail'.

Initially, it meant 'a nail for a door', but over time it evolved to retain that literal sense and also to appear in figurative usage, most notably in the idiom 'dead as a doornail' meaning 'completely dead'.