- a cardinal number, 10 times 3.
- a symbol for this number, as 30 or XXX.
- a set of this many persons or things.
- Printing, Journalism. 30-dash.
- thirties, the numbers, years, degrees, or the like, from 30 through 39, as in referring to numbered streets, indicating the years of a lifetime or of a century, or referring to degrees of temperature: He works in the East Thirties. She must be in her thirties. The temperature was in the thirties yesterday.
- amounting to 30 in number.
Origin of thirty
- the cardinal number that is the product of ten and threeSee also number (def. 1)
- a numeral, 30, XXX, etc, representing this number
- (plural) the numbers 30–39, esp the 30th to the 39th year of a person's life or of a century
- the amount or quantity that is three times as big as ten
- something representing, represented by, or consisting of 30 units
- amounting to thirtythirty trees
- (as pronoun)thirty are broken
Word Origin and History for thirtiest
early 15c. metathesis of Old English þritig, from þri, þreo "three" + -tig "group of ten" (see -ty (1)). Cf. Old Frisian thritich, Old Saxon thritig, Dutch dertig, Old High German drizzug, German dreissig. Thirty Years' War (1842) was a religious power struggle waged 1618-48, mainly on German soil. The symbol -30- as printer and telegrapher's code to indicate the last sheet or line of copy or a dispatch is recorded from 1895. In 20c. jargon of journalism, it came to be a traditional sign-off signal and slang word for "the end."