When should the plural form of the nouns combustible, material and liquid be used?

  • I don't see what's so unclear about this question; it's about whether and why adjectival nouns should be treated as countable.
    – phenry
    Commented May 9, 2014 at 18:00
  • @phenry: the question is unclear because its very premise is wrong. That combustible, material or liquid "may not adopt a plural form" is a rather nonsensical thing to say. And the rest is just common sense. When you are talking about one car, bird, liquid, or combustible, you use the singular. When you are talking about several cars, birds, liquids, or combustibles, you use the plural. If the OP thinks that for some reason you generally can't say "liquids" or "cars", then clarifying why they think so is not too much to ask for.
    – RegDwigнt
    Commented May 9, 2014 at 18:38
  • @RegDwigнt - If the premise is wrong, then the answer is "Your premise is wrong, and here's why." The three example words given all originated as adjectives but came to be used as nouns through metonymy. Clearly, the questioner is interested in understanding whether there are rules regarding the countability of such words, and what those rules might be. She gets the explanation wrong, but it's an understandable error, and a legitimate question. Don't penalize the asker for not knowing what metonymy is; that's what questions are for.
    – phenry
    Commented May 9, 2014 at 19:09
  • @phenry The title indicates that OP is concerned about the mass / count interface rather than 'behaviour of nouns having the same forms as their adjectives'. And this has been covered. Commented May 9, 2014 at 20:04

2 Answers 2


The plural form is used when the speaker wishes to emphasize a reference to different types of the mass noun in question.

At least in Am. E., "combustible" most often plural when it is used as a noun ("Put the combustibles in that closet") unless you are really singling out one category ("Is gasoline a combustible?", and even that sounds a little odd).

Since it is used more and is a more general term, "material" sometimes can refer to more than one type, where it is just referring to general stuff ("We'll need more material to build a house") but could just as easily be plural if you want to emphasize that it's not just one type ("We'll need more materials to build a house"). Liquid is similar, "Liquids go under the sink" implies a grouping of different liquids, but if it is all of one type, or the type is not important, then singular: "The host of You Can't Do That On Television was covered in liquid".


There is a very common construction in English that pluralizes mass nouns.
Of course, mass nouns don't take plurals normally, but that's the point -- if an unused
construction is floating around, it's very likely to be appropriated for special purposes.
There is no grammatical difference; mass nouns form plurals just like count nouns.

So countification of a mass noun X normally takes one of these semantic shapes:

  1. Vast extenses of X: the seas, the deserts, the slops, the shits
  2. Several different kinds of X: seven liquids, three combustibles, eighteen materials
    (This is the second kind.)

There is also massification of a count noun Y, relating to some property of Y:

  • more leg, not so much airbrush, dinner all over the wall

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.