Thir·ty n.; pl. Thirties
1. The sum of three tens, or twenty and ten; thirty units or objects.
2. A symbol expressing thirty, as 30, or XXX.
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thirties
n 1: the time of life between 30 and 40 [syn: mid-thirties, thirty-something]
2: the decade from 1930 to 1939 [syn: 1930s]