Definition from Wiktionary, the free dictionary
- (of the decade) 'thirties
- plural of
- (plural only) A decade starting with the year xx30, most usually the decade from 1930 to 1939.
- (plural only) The decade of one's life from age 30 through age 39.
- He looked to be in his thirties.
- (temperature, rates, plural only) The range between 30 and 39.