'Thirties' definitions:

Definition of 'thirties'

From: WordNet
noun
The time of life between 30 and 40 [syn: thirties, mid- thirties, thirty-something]
noun
The decade from 1930 to 1939 [syn: thirties, 1930s]

Definition of 'Thirties'

From: GCIDE
  • Thirty \Thir"ty\, n.; pl. Thirties.
  • 1. The sum of three tens, or twenty and ten; thirty units or objects. [1913 Webster]
  • 2. A symbol expressing thirty, as 30, or XXX. [1913 Webster]