the fifties[plural] (also the '50s, the 1950s) the years between 1950 and 1959 （二十世纪）五十年代 Standards of living rose in the fifties. 50年代生活水平提高了。
the early/mid/late fifties The play was written in the late fifties. 该剧创作于50年代后期。
→ the fifties at fifty(1)