In computer science we talk about binary trees as connections of nodes which of which have either zero or exactly two children. Furthermore we talk about "the parent node of a child", "the left child node of a parent", and "the right child of a parent". If I want to talk about both left and right, should I say "both child nodes" or "both children nodes"? As a native English speaker, "both children nodes" sounds more natural. Furthermore I'd say "both these nodes", not "both this nodes".

Another example is if I'm talking about member of a club: I'd say "This rule applies to all women members", not "This rule applies to all woman members".

My guess is that if I'm using a noun as an adjective, and the noun has an irregular plural form, that plural form can be used as an adjective. However, if I'm using a word which is an adjective only the singular form of the adjective can be used. "all women members" but "all female member" and never "all females members". Here female is really an adjective, not simply a noun being used as an adjective.

Or does it rather have to do with the fact that the "en" ending marks an irregular genitive form in Old English, and this usage as an adjective is just a vestige that old usage?

Or perhaps is this just an artifact of my particular dialect, and not standard English? Whatever that means...

Which is correct? "both child nodes" or "both children nodes"? Or do they perhaps have different meanings?

  • 4
    We don't say teethache, teethpaste, teeth decay, mice trap, micehole. So it definitely doesn't apply to irregular plurals in general. Oct 12, 2018 at 12:09
  • Google ngram definitely prefers "women members" to "woman members".<iframe name="ngram_chart" src="books.google.com/ngrams/…" width=900 height=500 marginwidth=0 marginheight=0 hspace=0 vspace=0 frameborder=0 scrolling=no></iframe>
    – Jim Newton
    Oct 12, 2018 at 12:16
  • Also notice that "children members" was more popular than "child members" until the year 1930 <iframe name="ngram_chart" src="books.google.com/ngrams/…" width=900 height=500 marginwidth=0 marginheight=0 hspace=0 vspace=0 frameborder=0 scrolling=no></iframe>
    – Jim Newton
    Oct 12, 2018 at 12:17
  • Google ngram search of "women soldiers" and "women doctors" shows the "women" form far more popular throughout history than the corresponding"woman" forms.
    – Jim Newton
    Oct 12, 2018 at 12:23
  • Plural "women doctors", but singular "lady doctors"!
    – BillJ
    Oct 12, 2018 at 13:48

1 Answer 1


Normally one doesn't use plural forms in noun compounds unless there's something idiomatic involved. It's not *shoes store, for instance, even though nobody ever buys just one shoe there.

So, in an actual noun compound, one would say in all child nodes of X; but if one omits node because it's obvious in the context, one would say in all children of X.

  • 2
    Yes John, that is the very point I'm pointing out. I don't think the rule is universal. The rule of using the singular form of a noun to modify a plural noun, is not universal. "Women doctors" for example, "Women soldiers". I wonder if it is related to the "en" ending. I wonder interpret "Women doctors" as doctors who are female, but "woman doctors" as gynecologists, even if that sounds a bit rude.
    – Jim Newton
    Oct 12, 2018 at 15:15
  • There are any number of exceptions -- maths homework, men admirers -- but they're all somewhat idiomatic, either in their form (as you suggest) with men, women, and children, or with a non-plural -s, as in maths, physics, or ethics. BTW, woman doctor does not mean 'gynecologist', at least not with the same stress pattern as women doctors -- it requires that woman be stressed instead of doctor, which is the norm in N-N compounds. Oct 12, 2018 at 15:36
  • 1
    I would note that you would say female doctors and female soldiers, not females doctors, etc. (Also, in my experience -- west coast US -- women doctors is rare; female doctors is more common; doctors is probably best.) Oct 12, 2018 at 16:42
  • 2
    Yes, Roger, nobody disputes that female takes no s when used as a plural adjective. Still, I suspect there is some grammar issue here. There is no "Society of Woman Engineers" rather there is a "Society of Women Engineers". We need more women politicians. Not: we need more woman politicians. However, we need more politician women, and never we need more politicians women. Certainly something is happening here.
    – Jim Newton
    Oct 12, 2018 at 20:28

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