fifties
n. plural-only A2 Elementary US //ˈfɪftiz// UK //fˈɪftɪz// fifties
n. the years between 50 and 59 in a century, or the age between 50 and 59 in a person's life.
n. the decade between the fiftieth and sixtieth years of a century, or the period of life between the ages of fifty and sixty.
Rock and roll music became very popular during the fifties.
My father is in his late fifties and is already planning his retirement.
The economic boom of the fifties transformed the suburban landscape, leading to a surge in car ownership and the growth of middle-class consumerism.
Usage
Always plural; takes a plural verb when referring to the decade or age range.
Pitfall
He is in his fiftyHe is in his fiftiesWhen referring to a person's age range or a decade, the plural form must be used.