The other day I came across this page and found a phrase strange to me.

The Britannica Dictionary

a/one thousandth of a second = one one-thousandths of a second [= 1/1000 second]

The plural "s" confused me so much. Then, I checked the hundred entry of the same site.

one hundredth of a second = one one-hundredth of a second [= 1/100 second]

There is no plural "s" with "hundredth"! Now I'm relieved. The writer must have made a mistake. "One one-thousandth of a second" (without s) should be right.

But I checked a news site to make sure.

  • But Montgomery is the world record with a time of 9.78 seconds, one one-hundredths of a second faster than Greene's best time. (New York Post)

  • In one of the most thrilling 100-meter finals in Olympic history, Gatlin won gold by one one-hundredths of a second. (New York Post)

  • She finished fourth in the trials with a time of 11.11, just one one-hundredths of a second behind third-place finisher Lauryn Williams. (New York Post)

Now I'm totally confused again. Somebody help me (an English teacher from Tokyo). Both are OK? Why can you make it plural?

  • 8
    I agree with you- It shouldn’t be plural there.
    – Jim
    Jun 24, 2022 at 6:09
  • 1
    It looks odd, but the units are one thousandths of a second. Jun 24, 2022 at 6:43
  • 2
    @Jim I agree, "three one-thousandths of a second" would be correct since there are more than one of the units of time, however "one three-thousandths of a second" would be incorrect as there is only one of the units of time. It's a typo, even dictionaries aren't immune to typographical errors.
    – BoldBen
    Jun 24, 2022 at 6:47
  • 3
    @WeatherVane I disagree, the unit is one-thousandth of a second, it's only plural if there are more than one of them. Why should a thousandth be any different linguistically from a quarter, a tenth, a ninety-second, a hundred-and-fiftieth or any other fractional unit. It's a typo.
    – BoldBen
    Jun 24, 2022 at 6:52
  • 1
    @BoldBen the dictionary's examples are one thousandth of a second, and one one thousandths of a second. So the question "How many one thousandths of a second?" could be answered "One one thousandths of a second." Perhaps this is the difference between casual speech and a formal unit. "We were going at one mile per hour" and "the velocity was one miles/hour". Jun 24, 2022 at 7:01

1 Answer 1


This seems simple:

We need to distinguish between

a/one {[one] thousandth} = 1/1000

two {[one] thousandths} = 2/1000

a/one {two thousandth} = 1/2000

two {two thousandths} = 2/2000

  • 1
    It is more scholarly to address a challenged entry in a recognised resource with references supporting the counterclaim. If this is merely 'simple', migration should be the option. Jun 24, 2022 at 13:41
  • Edwin Ashworth: Does anyone say "one one-fifths of a second"? - No. The Britannica entry is simply wrong. Note the OP's comment after checking 1/100ths: The writer must have made a mistake. Indeed they must - and you agree. My examples show the correct use and I think you will agree. I offer you Samuel Johnson: "You may scold a carpenter who has made you a bad table, though you cannot make a table. It is not your trade to make tables.”
    – Greybeard
    Jun 24, 2022 at 14:17
  • Not my DV, by the way; I try to use balance. Jun 24, 2022 at 14:45
  • 1
    @Greybeard - I think Edwin's point was that if it's so basic as not to need references, then it should go to ELL. I've often wondered if there's a way to codify which things should be migrated and which not, and that seems like it might work. Jun 25, 2022 at 20:54

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