As mentioned in other posts (like here), words which contain an 'ou' in their British spelling are typically spelled with an 'o' in the American equivalent. I'm interested in the reasoning and consistency of this rule.

My understanding is that the change was made to simplify things. If that is the case, the simplest result would surely be to make the change in all places. Yet, it seems the simplification is not applied to suffixes:

  • 'humourous' or 'homorous' but not 'humoros'
  • 'odourous' or 'odorous' but not 'odoros'

I grew up in South Africa and now live in Australia, both of which teach British spellings. I'm comfortable with dropping the 'u' in the root, but it looks wrong in the suffix. Is that because I'm just not acclimated to seeing the simplified suffixes, or is there something fundamentally wrong with simplifying the suffix - perhaps why they were never adopted in the first place?

  • If by "simplify things" you mean "shorten words", then no, that is not the reason. (E.g., "honor" and "color" were once very common in Britain, before "honour" and "colour" became standard.) And yes, there is something wrong with simplifying that suffix, because in AmE it is properly "-ous". I'll leave it at that, because good discussions of this issue can be found on various websites. Feb 9, 2022 at 1:29
  • The British spelling is humour but humorous - similarly with odour. Feb 9, 2022 at 8:51

1 Answer 1


All of the relevant words are spelled with "(o)ur".

You're right to see a certain inconsistency in the lack of simplification of words spelled with "ou" before other letters. Per Wikisource, Noah Webster, one of the big influential figures in the development of distinct American spelling standards, gave the following reasons for his choice of "or" spellings in the "Orthography" section of his Compendious Dictionary of the English Language:

  • Using "-or" makes spelling more consistent by bringing the spelling of "-o(u)r" words in line with the spelling of existing words that were already spelled with "-or" all the time by everybody
  • The spelling "our" is inadequate because it is "neither Latin nor French, nor calculated to exhibit the English pronunciation"
  • It is an "absurdity" to have -our in the spelling of words that are used as the base of words spelled with -or-, such as superiority, inferiority

The second and third justifications would apply equally well to the ending -ous: we write curious even though "ou" corresponds neither to the Latin spelling, nor the modern French spelling, nor the modern English pronunciation, and even though the derivative curiosity is spelled with just "o".

So I think the reason for not changing the spelling of -ous words to -ous is that even though -ous was not a particularly simple spelling, it was generally consistent already among words of this type. There weren't a large number of preexisting words that were already spelled with "-os" and pronounced the same as the words spelled with "-ous".

In contrast, the spelling "-or", pronounced the same as "-our", existed already for a long time before Webster's efforts to reduce the use of "-our".

Here's an article by Ben Zimmer about the gradual rise of -or spellings: "Why Americans Celebrate Labor (and not Labour) Day", September 7, 2009, Vocabulary.com Blog Word Routes

  • 2
    Old French did contain the -ous suffix, which contributed to the -ous suffix in Modern English. Feb 9, 2022 at 1:47
  • @MarcInManhattan: That's why I included the word "modern" when I wrote "'ou' corresponds neither to the Latin spelling, nor the modern French spelling". Webster might not have even been aware though of the origins of "ou" in French, since he seems to have incorrectly believed that forms like "honour" arose from blending Latin "honor" and modern French "honeur"
    – herisson
    Feb 9, 2022 at 1:50
  • 1
    Yes, I certainly wasn't disagreeing with you, just adding a note that I thought might be helpful for people trying to understand where that suffix came from. Feb 9, 2022 at 2:11

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