Our numbers have a specific two-letter combination that tells us how the number sounds.

For example

  • 9th
  • 3rd
  • 301st

What do we call these special sounds?

  • 8
    From Wikipedia: An onomatopoeia [from the Greek ὀνοματοποιία; ὄνομα for "name" and ποιέω for "I make"]; adjectival form: "onomatopoeic" or "onomatopoetic") is a word that phonetically imitates, resembles or suggests the source of the sound that it describes. Like oink, tick tock. Not applicable here. Commented Aug 22, 2014 at 22:02
  • 5
    Just a small remark: According to the English typography, the ordinal indicators are not written in superscript. In French or Spanish you do that, not in English. It's only Microsoft Word that implemented the feature years ago and since then, people think it's correct.
    – yo'
    Commented Aug 22, 2014 at 22:22
  • 9
    It's a suffix. The way it's printed varies, but it's the ordinal suffix that distinguishes an ordinal number from the corresponding cardinal number. Commented Aug 22, 2014 at 23:58
  • 11
    @tohecz Er, says who?! I read those forms in English text long decades before Micosoft Word ever cursed the world with its existence. Plus you’re wrong about French and Spanish: those ones up there are uniquely English. You can only have a 3ʳᵈ wife or 3ʳᵈ husband in English alone; in Spanish you’d have a 3ª esposa or a 3º marido, whatever suits your fancy. Do not let the tyranny of the typewriter cast out everything we ever knew about typography, which is something else altogether.
    – tchrist
    Commented Aug 23, 2014 at 5:48
  • 3
    @tohecz You are correct that in the US they were baseline in C.20 , but historically they are superscript in English - it's a style of abbreviation, e.g. 'equation'->'eq^n' (superscript may be underlined too). en.wikipedia.org/wiki/Ordinal_indicator#English
    – OJFord
    Commented Aug 24, 2014 at 0:02

4 Answers 4


It's an ordinal indicator:

In written languages, an ordinal indicator is a letter, or group of letters, following a numeral denoting that it is an ordinal number, rather than a cardinal number. Historically these letters were "elevated terminals", that is to say the last few letters of the full word denoting the ordinal form of the number displayed as a superscript. The exact letters used vary in different languages.

(source: Wikipedia)

  • 1
    In my experience we do; today is August 22nd. If I were British or Irish, today would probably be 22 August. Commented Aug 22, 2014 at 21:01
  • 4
    @WS2 In speech, very nearly always. In writing, much less so. I think what may be going on is that one just assumes that “June 1” is pronounced “June First”, or “4 July” as “the Fourth of July”. So your perception that they are not so much used in America may be from the lazy or abbreviated or “assumed” written versions not the actual oral ones. So for example if you were born on February 13, you would say aloud that you were born on February Thirteenth — never on February *Thirteen, which doesn’t even sound grammatical for some reason.
    – tchrist
    Commented Aug 22, 2014 at 22:12
  • 2
    @tchrist But where you do differ from us, both in spoken and written form, is that you omit the definite article. We would say 'on February the thirteenth', never 'on February thirteenth'.
    – WS2
    Commented Aug 22, 2014 at 23:00
  • 1
    @WS2 Hmm, that sure sounds more like Friday the Thirteenth ’round these parts. But I wonder: do you also say I saw him on February the first as well? If so, then things are weirder than I realized.
    – tchrist
    Commented Aug 23, 2014 at 5:53
  • 5
    @RoboKaren, no - as "the 22nd of August".
    – tobyink
    Commented Aug 23, 2014 at 12:37

In the case of 9th, the superscript shown is indeed called the 'ordinal indicator' as Matt Gutting has noted in his answer.

The addition of -th/ -eth relates to numbers 4 to 20 (and similarly,) and is a suffix to the cardinal number.

However, as in the second and third examples, the rd & st simply come from the right-end of the word for the ordinal number:

3rd: thi rd

301st: (three-hundred-) fir st (shouldn't that be 301 th ?, I'm not going there).

Of course, in general, we call all these superscripts 'ordinal indicators,' and "suffixes," 'ordinal suffixes.' (We can see that there's no suffix as such until we come to 4, as we have ordinal names.)

  • I would regard the "nd" in "second" as a suffix on the number "3", like the "th" in "20th". For example, I would suggest that "VIP" [Very Important Person] is made plural by adding a "-s" suffix, even though the resultant phrase [Very Important People] doesn't contain the letter "s" anywhere within it.
    – supercat
    Commented Aug 23, 2014 at 20:15
  • @supercat VIPs: Very Important Persons -- where are the people coming from :) Even otherwise, you can pluralize an abbreviation by itself, cf. RADARs.
    – Kris
    Commented Aug 24, 2014 at 4:57

First, these abbreviations are not onomatopoeia.

In fact, your question is about writing rather than sounds.

In the written number 2nd, the letters nd are the superscript.

More generally, these letters form the ordinal indicator in english.

  • The question has been edited. My answer applies to the question as I saw it, with the superscripts. Commented Aug 23, 2014 at 18:43

These are ordinal suffixes.

Ordinal formatter: add ordinal suffixes (-st, -nd, -rd, -th) to numbers. finzi.psych.upenn.edu

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