[ thur-tee ]

noun,plural thir·ties.
  1. a cardinal number, 10 times 3.

  2. a symbol for this number, as 30 or XXX.

  1. a set of this many persons or things.

  2. Printing, Journalism. 30-dash.

  3. 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 thrīthree + -tig-ty1; cognate with Dutch dertig,German dreissig,Old Norse thrjātīu Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use thirty in a sentence

British Dictionary definitions for thirty


/ (ˈθɜːtɪ) /

nounplural -ties
  1. the cardinal number that is the product of ten and three: See also number (def. 1)

  2. a numeral, 30, XXX, etc, representing this number

  1. (plural) the numbers 30–39, esp the 30th to the 39th year of a person's life or of a century

  2. the amount or quantity that is three times as big as ten

  3. something representing, represented by, or consisting of 30 units

    • amounting to thirty: thirty trees

    • (as pronoun): thirty are broken

Origin of 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