'on-site' originates from the combination of 'on' and 'site', where 'on' meant 'in a position above' and 'site' referred to 'a place or location'.

'on-site' evolved from the Old English 'on' and the Latin 'situs', eventually becoming the modern English term 'on-site'.

Initially, it meant 'at the location', and this meaning has largely remained the same in modern usage.