noun, plural thir·ties.
  1. a cardinal number, 10 times 3.
  2. a symbol for this number, as 30 or XXX.
  3. a set of this many persons or things.
  4. Printing, Journalism. 30-dash.
  5. 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.
  1. amounting to 30 in number.

Origin of thirty

before 900; Middle English thritty, Old English thrītig, equivalent to thrī three + -tig -ty1; cognate with Dutch dertig, German dreissig, Old Norse thrjātīu Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for thirties

Contemporary Examples of thirties

Historical Examples of thirties

  • Oh, sure, we were in our thirties, but who would have suspected that?

    The Man the Martians Made

    Frank Belknap Long

  • These may be of any age from eighty odd to the bitter thirties.

    Another Sheaf

    John Galsworthy

  • He was much younger than middle-aged, really—somewhere in his thirties.

    Ten From Infinity

    Paul W. Fairman

  • A tall, fair man still in his thirties, had stopped and raised his hat.

    The Mask

    Arthur Hornblow

  • This was frontier when we came here in the thirties; we belong here.

    Winning the Wilderness

    Margaret Hill McCarter

British Dictionary definitions for thirties


noun plural -ties
  1. the cardinal number that is the product of ten and threeSee also number (def. 1)
  2. a numeral, 30, XXX, etc, representing this number
  3. (plural) the numbers 30–39, esp the 30th to the 39th year of a person's life or of a century
  4. the amount or quantity that is three times as big as ten
  5. something representing, represented by, or consisting of 30 units
    1. amounting to thirtythirty trees
    2. (as pronoun)thirty are broken

Word Origin for thirty

Old English thrītig; see three, -ty 1
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for thirties

1827 as the years of someone's life between 30 and 39; 1830 as a decade of years in a given century. See thirty.


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."

Online Etymology Dictionary, © 2010 Douglas Harper