thirties (root: thirty)

Noun thirties has 2 senses

• thirties(n = noun.time) mid-thirties, thirty-something - the time of life between 30 and 40;
is a kind of time of life
is a part of adulthood, maturity

• thirties(n = noun.time) 1930s - the decade from 1930 to 1939;
is a kind of decade, decennary, decennium