The grammar of mass and count nouns

Mass nouns are often the names of substances like water, wood and air that we can measure on a continuous scale. Count nouns, on the other hand, generally label things that come in discrete wholes that we can count like children, houses and hats. To put it simply, the distinction between mass and count is one between stuff and things.

You can usually guess whether a noun will be of the mass or count variety from its meaning, but what ultimately determines whether a word is classified as a mass noun or count noun is the way it functions grammatically.

Mass nouns are always singular, so like singular count nouns, they trigger singular agreement. Mass nouns also have something in common with plural count nouns because continuous substances and groups of countable objects can both vary in quantity. These factors partly explain which determiners you can use with mass nouns and how they compare with the determiners you can use with singular and plural count nouns:

Articles: A vs. AN and THE vs. THE

A versus AN
When learning a second language, people usually learn the written form at the same time as the spoken form. With English, this can be confusing because the spelling is very irregular. This is especially true for the rule about when to use a versus an, but if phrased in terms of pronunciation rather than spelling, the rule is extremely simple:

RULE: Use a before words beginning with a consonant sound and an before words beginning with a vowel sound.

The spelling often agrees with the phonetic rule, as in the following example:

• a cat
• an old cat

But the spelling isn't always so kind:

• a university (because university begins with the y sound of youth)
• an umbrella (because umbrella begins with the u sound of up)
• a xylophone (because xylophone begins with the z sound of zoo)
• an x-ray (because x-ray begins with the e sound of extra)
• a hat (because the h is pronounced)
• an hour (because the h is silent)

The rule is about pronunciation rather than spelling, so the rule still holds perfectly in these examples, even if the spelling is unhelpful. If you know how to pronounce the next word, you'll always know whether to use a or an. Of course, for speakers of languages like Italian and French who have trouble hearing the h sound, this isn't so simple.

Note that there are a few people who believe that an should be used before certain words that begin with an h sound in modern English, and consider this 'proper' educated usage. The most common example of this occurs with the word historic:

• an historic event (rare usage)

The belief that this is grammatically correct is probably due to another unhelpful effect of spelling. The reason we can find 'an historic' written in old texts is that there was a time when the h of historic was silent in many people's speech. It's like the word herb in modern varieties of English. Some people pronounce the h and some don't. Those who pronounce the h write 'a herb', and those who don't pronounce the h write 'an herb'. Text preserves the spelling, but not the pronunciation that goes along with it, so after the pronunciation of historic settled on its modern form, people who saw 'an historic' written in older texts probably mistook this for a rule that applied to modern pronunciation.

In general, if native speakers have to be taught a rule that doesn't come naturally, there is probably something fishy about the rule. Misguided rules of this kind are almost not worth mentioning, except that people benefit from an awareness of them when they, for example, end up working for people who believe them.

THE versus THE
Like a, the pronunciation of the varies depending on whether the next word begins with a vowel or consonant sound. Before a word beginning with a consonant sound, the vowel of the is usually reduced to what's called a schwa, represented by the ə symbol in the International Phonetic Alphabet:

• the cat (pronounced ['ðə] with a short middle vowel)
• the old cat (pronounced ['ði] to rhyme with bee)

This is one of those details that native speakers almost never notice about their own language (again probably because it's not reflected in the spelling) and which they never need to be taught.

Weirdness with plurals

The grammatical distinction between singular and plural does not map perfectly onto the meanings one and more than one.

One way to check whether a noun phrase is singular or plural is by seeing whether it triggers singular or plural agreement with a verb when it appears as the subject of a sentence:

• Singular: This monkey likes bananas. [and not This monkey like...]
• Plural: These monkeys like bananas. [and not These monkeys likes...]

Another way, also illustrated in the above examples, is by looking at whether a singular or plural determiner is used (in these examples, the determiner this is singular and the determiner these is plural), though with a determiner like the, the form doesn't change, and there are a few cases where the determiner appears to be singular, but plural agreement is triggered:

• Plural: A few/dozen/hundred/million monkeys like bananas.