THIRTIES

[plural] [noun]The thirties is the range of temperature between 30° and 39°.The temperature is expected to be in the thirties tomorrow.The thirties is also the period of years between 30 and 39 in any century.These dresses were fashionable in the thirties (= between 1930 and 1939).A person's thirties are the period in which they are aged between 30 and 39.My brother is in his thirties.