'fiftieth' originates from Old English, specifically the word 'fīftig,' where 'fīf' meant 'five' and '-tig' meant 'group of ten.'

'fīftig' transformed into the Middle English word 'fiftieth,' and eventually became the modern English word 'fiftieth.'

Initially, it meant 'the ordinal number of fifty,' and this meaning has largely remained the same in modern usage.