Why "material" is countable?

Question

"material" has different meanings, one of which is "cloth used for making clothes, curtains, etc." according to Oxford dictionary There is an example in which material is plural

The military uses synthetic materials for clothing because they're more durable than cotton.

I wonder why they have to use materials in this case. Normally, if a word can be both countable and uncountable and its singular form is rarely used, the dictionary will probably note that "usually ....(that word in plural form), and either plural form or uncountable form will mean the same, but in the entry for material they don't. Therefore I suppose "a material" can be used. It's obvious that we can't count cloth so why its synonym, material, is countable? I can't come up with any cases where material can be in singular form.

Answer 1

"Material" can refer to more than fabric/cloth. It means any substance that can be used to make something else. For example, you could say that: "Iron is the material used to make weapons".

When "material" is singular, it refers to a single substance: "The woman went into the store to buy material to make dresses." When it is plural, it means more than one type of substance: "Iron, nickel, and copper were the materials the blacksmith worked with daily."

In the first example, all the "material" the woman is buying is understood to be cloth/fabric, so there is only one kind of "material" being referred to, and the word is singular (okay, so she might be buying a few different types of fabric, but the speaker is generalizing, lumping all fabric together into a single category).

In the second example, and in your sentence in the question, the speaker is making a distinction between various types of substance (in your example, they are talking about various synthetic substances, maybe different types of fabric, or maybe fabric plus other substances) and therefore they are using the plural: "synthetic materials", highlighting that there are various synthetic substances, as opposed to "synthetic material" which would be only one type or category of synthetic substance.