from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The cardinal number equal to 3 × 10.
  • n. A decade or the numbers from 30 to 39: They settled down in their thirties. The temperature fell into the thirties.
  • n. The decade from 30 to 39 in a century.
  • n. An indication of the end of a news story, usually written 30.
  • n. Sports The second point that is scored by one side in tennis.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The cardinal number occurring after twenty-nine and before thirty-one, represented in Arabic numerals as 30.
  • n. A rack of thirty beers.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Being three times ten; consisting of one more than twenty-nine; twenty and ten.
  • n. The sum of three tens, or twenty and ten; thirty units or objects.
  • n. A symbol expressing thirty, as 30, or XXX.

from The Century Dictionary and Cyclopedia

  • Being thrice ten, three times ten, or twenty and ten.
  • n. The number which consists of three times ten.
  • n. A symbol representing thirty units, as 30, XXX, or xxx.
  • n. In printing and telegraphy, the last sheet, word, or line of copy or of a despatch.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the cardinal number that is the product of ten and three
  • adj. being ten more than twenty


Middle English thritty, thirty, from Old English thrītig; see trei- in Indo-European roots.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Old English þritiġ (Wiktionary)



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