'nineteen-fifties' originates from Modern English, specifically the compound of the numerals 'nineteen' + 'fifties', where 'nineteen' denotes the number 19 and 'fifties' denotes the decade beginning with 50 (the years 1950–1959).

'nineteen-fifties' developed in the 20th century as a spoken and written compound to name the decade; it is parallel to numeric decade forms like 'the 1920s' or 'the 1980s' and often appears interchangeably with the shortened numeric form 'the 1950s'.

Initially formed simply as a numeric label for years, it came to be used more broadly to evoke the cultural and historical associations of that decade (e.g., 'music of the nineteen-fifties').