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See also: ordinal-number



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ordinal number (plural ordinal numbers)

  1. (grammar) A word that expresses the relative position of an item in an ordered sequence.
    First, second and third are the ordinal numbers corresponding to one, two and three.
  2. (arithmetic) A number used to denote position in a sequence.
    In the expression a3, the "3" is an ordinal number.
  3. (mathematics) A generalized kind of number to denote the length of a well-order on a set.



Coordinate termsEdit


The translations below need to be checked and inserted above into the appropriate translation tables, removing any numbers. Numbers do not necessarily match those in definitions. See instructions at Wiktionary:Entry layout#Translations.

Usage notesEdit

On ordinal number usage:

  • Ordinal numbers are generally construed as adjectives preceding (countable) nouns in singular:
    eleventh day
  • Ordinal numbers are used for fractions as (countable) nouns, and for exponents usually followed by power and that numeral:
    two fifths,  
    two to the minus twenty-first power,  
    six to the third,  
  • Ordinal numbers are generally considered to be ordered from high to low, so that first place is considered highest, and fifth is lower than second. Degree is an exception.
  • Ordinal numbers corresponding to numbers higher than 20 use cardinal numbers for all the places preceding the final ordinal part:
    twenty-first or 21st, occasionally XXI
    one hundred fifteenth or 115th, occasionally CXV
    thirty-three thousandth or 33,000th
  • If an ordinal is followed by a plural noun, the two word phrase refers to a set of items described by the phrase in singular. For example second homes refers to a set of homes which are considered a "second home."
    Many households have third cars.

See alsoEdit