ordinal number (plural ordinal numbers)
- (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.
- (arithmetic) A number used to denote position in a sequence.
- In the expression a3, the "3" is an ordinal number.
- (mathematics) A generalized kind of number to denote the length of a well-order on a set.
grammar: word used to denote relative position in a sequence
- Afrikaans: (please verify)rangtelwoord
- Mandarin: 順序數 (zh), 顺序数 (zh) (shùnxùshù), 序數 (zh), 序数 (zh) (xùshù), 序數詞 (zh), 序数词 (zh) (xùshùcí)
- Crimean Tatar: sıra sayısı
- Czech: řadová číslovka f
- Danish: ordinaltal n, ordenstal (da) n
- Dutch: (please verify)ranggetal n, rangtelwoord (nl) n
- Finnish: järjestyslukusana, ordinaalilukusana
- French: nombre ordinal m (pl. nombres ordinaux)
- Georgian: რიგითი რიცხვითი სახელი (rigiti ricxviti saxeli)
- German: Ordnungszahl (de) f, Ordnungszahlwort (de) n; Ordinale n, Ordinalzahl (de) f
- Hungarian: sorszámnév (hu)
- Irish: (please verify)orduimhir f
- Japanese: 序数詞 (じょすうし, josūshi), 序数 (ja) (じょすう, josū)
arithmetic: number used to denote position in a sequence
generalized kind of number to denote the length of a well-order on a set
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.