Thir·ty a. Being three times ten; consisting of one more than twenty-nine; twenty and ten; as, the month of June consists of thirty days.
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.
adj : being ten more than twenty [syn: 30, xxx]
n : the cardinal number that is the product of ten and three
[syn: 30, XXX]