thirty Thirty-nine Articles a series of points of doctrine historically accepted as representing the teaching of the Church of England. Adopted in 1571, the Articles often allow a wide variety of interpretation.
thirty pieces of silver the price for which Judas betrayed Jesus to the Jewish authorities, as told in Matthew 26:15; Judas is subsequently said to have repented, and to have thrown down the money in the temple before killing himself. Because it was regarded as blood money it could not be returned to the treasury; it was therefore used to purchase the potter's field.
thirty-something an unspecified age between thirty and forty; the term was widely publicized by the successful US television series Thirtysomething which from 1987 recounted the ups and downs and family lives of a group who had reached their thirties in the 1980s.
Thirty Tyrants the magistrates imposed by Sparta on Athens at the end of the Peloponnesian War; their repressive rule was ended when Critias, leader of the oligarchy, was killed, and democracy restored.
Thirty Years War a European war of 1618–48 which broke out between the Catholic Holy Roman emperor and some of his German Protestant states and developed into a struggle for continental hegemony with France, Sweden, Spain, and the Holy Roman Empire as the major protagonists. It was ended by the Treaty of Westphalia.

thir·ty / ˈ[unvoicedth]ərtē/ • cardinal number (pl. -ties) the number equivalent to the product of three and ten; ten less than forty; 30: thirty or forty years ago thirty were hurt thirty of her school friends. (Roman numeral: xxx, XXX.) ∎  (thirties) the numbers from thirty to thirty-nine, esp. the years of a century or of a person's life: a woman in her thirties she was a famous actress in the thirties. ∎  thirty years old: I've got a long way to go before I'm thirty. ∎  thirty miles an hour: doing about thirty.DERIVATIVES: thir·ti·eth / -i[unvoicedth]/ ordinal numberthir·ty·fold / -ˌfōld/ adj. & adv.