Mold vs. mould

  • American English has no mould, and British English has no mold. In other words, the word referring to (1) the various funguses that grow on organic matter or (2) a frame for shaping something is spelled the same in both uses, and the spelling depends on the variety of English.


    Of course, the spelling difference extends to derivatives such as moldy/mouldy and molding/molding and to the verb sense to shape with a mold. 

    Australian and Canadian English favor the British spelling, though mold is fairly common in Canadian publications.




    Inside, the rain had spawned black, green, and yellow mold that crawled the walls. [Atlantic]

    Obama has been more in the mold of George H.W. Bush and his secretary of state. [Daily Beast]

    If some of the insulation is intact, leave it in place unless it is moldy. [Boston Globe]

    Outside the U.S.

    Without air conditioning in a highly humid climate, mould could form. [Montreal Gazette]

    And Pretty Ballerinas is still making shoes in the mould of the original pair created in 1918. [New Zealand Herald]

    There’s no bread, and even the mouldy cheese has been chipped away at. [Scotsman]


    1. The fact that mold appears in Canadian spelling both contradicts the statement that mould is Canadian and the idea that there is a Canadian English. There seems to be a conspiracy amongst Eastern Canadian publishers to insist that there is an official Canadian way of spelling and that it is primarily English when not tainted by French. I don’t recognize it and refuse to let them dictate my spelling and pronunciation.

    2. There should be a different spelling for each meaning.

    3. o.0 I actually thought “mould” was for the growth, and “mold” was for molds that you set stuff in, like a chocolate mold.

    4. Since English is a language developed by useage, and the words are both used, they are correct by definition.

    5. So, basically “Mold” is correct, “Mould” is American (aka wrong).

      (why in both cases has american ENGLISH been put first? It almost implies that american ENGLISH was the original version!)

    6. Personally I think it would be most effective to adopt a different spelling for the object used in casting. from the 2nd definition Identifying a fungus growth on food. thus eliminating mold as a word with 2 entirely different definitions. While context is generally enough for one to identify the intended meaning. In some paragraphs where both meanings are possible, such as molding perishables such as food or paper products, It can lead to confusion.

      • SuperCritic says

        In New Zealand, “mold” is the spelling adopted when describing a form for casting a shape while “mould” is used when referring to the fungus. On the other hand, in America the “mould” spelling is occasionally used, but only when talking about the form for casting a shape, not when talking about the fungus. Basically, this word is all kinds of messed up.

    7. When I’m making cheese, I use a mould to mould the cheese, and then leave it in a box for mould to grow on it.

      Can someone please fix this to help define the two different stages in cheese making?

      • Nutty Professor says

        Sure … “When making cheese, I use a mold to form the cheese, then leave it in a box for mould to age it.”


      • make sure you wash between your toe before you start.

    8. I’ve seen some instances of ‘mould’ in the States, usually regarding architecture (for example, there’s a hardware store in Cambridge, MA that refers to ‘Moulding’ on its signs).

    9. Winston Smithers-Windsor says

      I find it utterly hilarious when Americans compare ENGLISH English with American English as if this were a valid, equal comparison. It isn’t! ‘mold’ and ‘color’ et al are simply WRONG! It doesn’t matter whether or not a menagerie of ‘no-history’, transient deluded ingrates misspell and mispronounce words.
      The color of the mold was green – I’m an American!

      • As a linguist, I have to point out that spellings have been changing as long as our language has been written down, and most of that change has taken place in Britain – just ask Dr. Samuel Johnson. As a Canadian, we get to pick the best from the American and British spellings, although if there is no clear winner, we typically default to the British. To me, both spellings are acceptable for both words. Historically speaking, the word for the shaping device comes from the Proto-Indo European root *med- ‘to measure’, while the term for the fungus probably derives from the root *meug- ‘mucus’. Based on this alone, I suggest that ‘mold’ be used for the device, and ‘mould’ be used for the fungus, since the PIE root also has a ‘u’ in it. However, I have noticed a trend that is the reverse of this, as is apparently already the case in the US according to some of the comments above. Whatever – as long as one spelling becomes associated with one meaning, the goal of differentiation has been achieved – at least in writing.

      • Ceci Pipe says

        Funnily enough the USA has kept a lot of older words that Britain lost, like using “fall” for autumn, making their vocabulary more historically accurate than anything in the UK. As for the simplification that was started in Britain and continued in the USA, though with a different focus outside the influence of Latin/Greek based British linguists.

    10. Brian Burnett says

      In Canada Mould is a fungus while Mold is what you shape items in during manufacturing.,, It is unfortunate that neither the UK (England) or the USA (get a name willya ?) have figured this difference out . lol

    11. JediWombat says

      “… derivatives such as moldy/mouldy and molding/molding…”

      I’m sure you meant “molding/moulding” ;)

    12. Or in this case, as seen above : (sic) “Of course, the spelling difference extends to derivatives such as moldy/mouldy and molding/molding and to the verb sense to shape with a mold.” The same spelling when you meant to spell it as ‘moulding’!

    13. “Funguses”?
      Now there is a whole ‘nother discussion….

    14. At least colloquially in Canada, “mould” is the fungus and “mold” is the frame for making things, though I’m not sure whether this is actually a formally-recognised rule or if it’s just common usage.

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