From Longman Dictionary of Contemporary Englishthirtythir‧ty /ˈθɜːti $ ˈθɜːrti/ ●●● S3 W3 number 1 HMNthe number 302 the thirties (also the '30s, the 1930s) [plural]TMCSH the years from 1930 to 1939 In the thirties, air travel really began to take off.the early/mid/late thirties The family sold the house in the early thirties.3 → be in your thirties4 → in the thirties —thirtieth adjective, pronoun her thirtieth birthdayOrigin thirty Old English thritig, from thrie “three”
