In programming I often step into cases where names of variables have to indicate a group of groups. How do I properly formulate them in terms of multiplicity word endings?

Examples (concrete questions):

  • "indices of sector vertices" I write as "sector vertex indices". Should it be "sector vertices indices"? I have to get rid of the "of" word because that is not in style.

  • in "sector vertex indices" does "sector" have to end in "-s" as a sign of identifying its feature later, like "sectors vertices"?

  • "names of variables" I would write as "variables names". That seems legit. What if i turn it into "program variables names"? What would be the correct writing of it?

Are there any known rules about these matters?

2 Answers 2


"These matters" concern noun-noun compounds. One rule is that the first noun must be singular, so it's "sector vertices," not "sectors vertices."

The other rule is to make sure that you don't mislead your reader. When you decide to use "variable names" instead of "names of variables," make sure that your context is clear enough that no one will think that by "variable names" you mean names that vary.

Be particularly careful when you stack the nouns. You can write the "Illinois state planning office department head" to mean the head of a department in the office for planning in the state of Illinois, but the more nouns in a row, the more likely your reader will get lost without some prepositional or other sign posts.

So, when you write "sector vertex indices," do you mean sector vertex-indices (that is, a type of index of sectors and the indexes are associated with vertexes) or do you mean sector-vertex indices (that is, a type of index of vertexes and it's the sectors associated with the vertexes). If there's no difference in context, leave the hyphens out.

  • "One rule is that the first noun must be singular". If it is a rule then it is broken occasionally. For example, media circus(es).
    – Avon
    Jun 27, 2015 at 21:06
  • No rules are universal.* "Media" is a collective noun. In the US, it would even take a singular verb. But no matter how thick the university's course catalog, it's a class schedule, not a classes schedule. (*See what I did there?)
    – deadrat
    Jun 27, 2015 at 21:20

If you had multiple boxes each containing multiple nails (boxes of nails) you surely would say they were "nail boxes" not "nails boxes". The latter sounds like it is possessive missing its apostrophe. The former is a noun as an adjective to a noun (nail box): it describes the type of box - boxes that contain nails.

I think in all your examples that is appropriate: that is really what you are doing - making one of the nouns an adjective to the other noun.

For "variable names", it is the kind of names (those names that name variables) so appropriate to use "variable" as an adjective to "name". "Variables names" sounds like the names of the variables (possessive) missing its apostrophe.

For "indices of sector vertices", the indices can be described as containing sector vertices so I would call them sector vertex (noun as an adjective) indices.

I believe there is no rule as to whether nouns as adjectives have to be singular but I suggest going with what sounds right and that is usually making the noun as an adjective singular and mainly because if it is plural it sounds possessive.

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