thirtya.[OE. thritty, AS. rtig, rittig; akin to D. dertig, G. dreissig, Icel. rjtu, rjtigi, rir teger, Goth. 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.()()n.1. The sum of three tens, or twenty and ten; thirty units or objects.()2. A symbol expressing thirty, as 30, or XXX.()