Stop telling people DATA is plural

The word data is almost universally used as a singular mass noun in English except among many professional writers and academics who insist that it is the plural of datum, a word that is almost non-existent in English outside discussions of whether data is a plural. The reason usually cited for treating data as a plural is that it was a plural in Latin, which is true but irrelevant since grammatical changes often occur when words are borrowed from one language to another. A perfectly analogous example is the word spaghetti which is a plural count noun in Italian but very clearly a mass noun in English, which is why native speakers of English say This spaghetti is cooked and not These spaghetti are cooked.

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:

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.