'enclosure' originates from Old French, specifically the word 'enclos' (past participle of 'enclore'), where 'en-' meant 'in' and 'clos/ clore' (from Latin 'claudere') meant 'to close'.

'enclosure' changed from Middle English 'enclosur' (or 'enclosure') and eventually became the modern English word 'enclosure'.

Initially it meant 'the action of closing in or the state of being closed in', but over time it also came to mean 'a fenced-off area' and 'an item enclosed with a letter'.