'Thirty' definitions:

Definition of 'thirty'

From: WordNet
adjective
Being ten more than twenty [syn: thirty, 30, xxx]
noun
The cardinal number that is the product of ten and three [syn: thirty, 30, XXX]

Definition of 'Thirty'

From: GCIDE
  • Thirty \Thir"ty\, a. [OE. thritty, AS. [thorn]r[imac]tig, [thorn]rittig; akin to D. dertig, G. dreissig, Icel. [thorn]rj[=a]t[imac]u, [thorn]rj[=a]tigi, [thorn]rir teger, Goth. [thorn]reis tigjus, i.e., three tens. See Three, and Ten, and cf. Thirteen.] Being three times ten; consisting of one more than twenty-nine; twenty and ten; as, the month of June consists of thirty days. [1913 Webster] [1913 Webster]

Definition of 'Thirty'

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]