1. The time of life between 30 and 40
   "By his mid-thirties, he had already become a successful entrepreneur";
   - mid-thirties, thirty-something
    
2. The decade from 1930 to 1939
   "The Great Depression affected many countries in the thirties";
   - 1930s

1. The cardinal number that is the product of ten and three
   "Thirty days hath September";
   - 30, XXX

Type of: decade, decennary [archaic], decennium, large integer, time of life

Part of: adulthood, maturity

Encyclopedia: Thirties