The sixth decade of a century: the 1850s, 1950s, 2050s, etc.
I will probably be dead by the fifties.
1954 June, R. Marchant, “Early Excursion Trains”, in Railway Magazine, page 427:
The fifties were the heyday of the excursion train, with the 1851 Exhibition naturally giving a great boost to such traffic.
2025 August 5, Danny Goldberg, “A Guest Post By Danny Goldberg: Culture, Empathy And Resistance”, in DownWithTyranny, archived from the originalon23December 2025: