# When are numbers nouns?

In my native language, Portuguese, numbers have officially been in various classes, from adjectives and nouns to "quantifiers" and determiners.

I'm thinking that perhaps we can't group them all, simply because they behave differently. For example, "ten" works differently from "million". Multiplying by 2, you get "twenty" and "two millions". A million is a noun, like a potato or a third; while "ten" is different. "Twelve" and "a dozen" are the same in meaning, but grammatically behave in different ways.

Why? In other languages, this happens with other words. Some may agree in gender/number with the object they quantify, like nouns do. Can we grammatically divide numbers in different classes? How would this work? Would another class be required? How would this system vary from language to language (I'd appreciate if you'd make a comparison between English and some other language of your choice)?

• As a monolingual English speaker, and writing off the cuff, I would say that English numeral terms are nouns when they stand for specific abstract quantities or for numerals. In "One and one make two," all the numeral terms are nouns that stand for abstract quantities. In "Write a three in the third box," the numeral term "three" stands for a numeral, i.e. a symbol that usually stands for a specific abstract quantity. Commented Aug 9, 2013 at 23:32
• I'm going to try to summarise the different questions i think you're asking here, just to make sure i'm following: (1) Why don't number words behave in a syntactically uniform manner? (2) If number words do cross-cut syntactic categories, which categories to they belong to (this raises interesting questions about the syntax/semantics interface, e.g. if number words are semantically uniform, why don't they behave the same syntactically?) (3) Do we need a distinct syntactic category 'numeral'? (4) To what extent to numeral systems differ cross-linguistically? Commented Aug 9, 2013 at 23:59
• @James, in "Write a three in the third box.", wouldn't the "three" be a noun, as it is substitutable be "word"? Commented Aug 10, 2013 at 14:28
• @PElliot, precisely my questions; only yours are written better. :) Should I edit the post and replace the last paragraph with those? Commented Aug 10, 2013 at 15:04
• If you like, but it's probably just me. I just wanted to check that i understood. Greville Corbett (1978: academia.edu/746864/…) argues all numerals are somewhere between nouns and adjectives - he tentatively claims that, universally, the numerals which are more noun-like are numerically higher than the numerals which are more adjective-like. For example, the numerals in English which take an article are numerically higher than those which don't. It's an interesting claim and it's totally mysterious to me why it would hold. Commented Aug 10, 2013 at 16:28

Each word is classified by what is permissible in the instances in which it appears. In English, "three" can be a noun, an adjective, a pronoun, or a numeral. I will use French as the second language in my examples. If a word can be replaced by another word without changing the grammar of the sentence, the two words have the same grammatical class in that instance.

### Noun

• I have a three.
• I have a (playing) card (with the value three).
• J'ai un trois.
• J'ai une carte (à jouer) (avec la valeur trois).

• I have three cats.
• I have small cats.

### Determiner (French)

• J'ai trois chats. (I have three cats.)
• J'ai des chats. (I have some cats.)

• J'ai les trois chats. (I have the three cats.)
• J'ai les petits chats. (I have the small cats.)

### Pronoun

• Three are eating.
• They are eating.
• Trois mangent.
• Ils mangent.

### Numeral

• One, two, three.
• One, two, four.
• Un, deux, trois.
• Un, deux, quatre.

Note: "numeral" can be hard to differentiate from the other classes. It doesn't work if you replace "three" with a word from a different class:

• One, two, three
• One, two, *card
• One, two, *some
• One, two, *small
• One, two, *they

So, "three" isn't a noun, an adjective, a pronoun, and a numeral at the same time, it is only one of those at a time. You should now be able to apply the same process in Portuguese to work out when numbers are nouns.

In regards to your question about the declination of numbers (i.e. whether they are invariable, can be singular or plural, etc.), note that some nouns are invariable (in certain contexts), and some have to be declined.

• I am drinking milk.

Not:

• I am drinking *a milk. (allowable if "a milk" is the ellipsis of "a serving of milk")
• I am drinking *milks.

It seems from your question that in Portuguese, "ten" is invariable, while "million" can be singular or plural. This doesn't change the grammatical class.