The Oxford English Dictionary defines the word fun as follows:
Diversion, amusement, sport; also, boisterous jocularity or gaiety, drollery. Also, a source or cause of amusement or pleasure.
Which word class does fun belong to? Well, it’s a noun, of course. What else could it be? The OED agrees.
However, the latest edition of the Oxford Advanced Learner’s Dictionary allows for fun to appear before nouns, as in this example:
There are lots of fun things for young people to do here.
Could fun be regarded as an adjective in this example? Well, maybe, but we mustn’t forget that, although adjectives are indeed typically placed before nouns, it is also possible for nouns to occur there, as in the phrases lunch menu, mattress protector, business trip, and so on, so this particular example doesn’t conclusively show that fun can be an adjective.
However, the dictionary has two further examples:
She’s really fun to be with
This game looks fun.
In the first of these examples fun is preceded by really, and this proves that it is an adjective, because the adverb really cannot modify nouns. In the second example fun occurs after look, and this again shows that fun is an adjective because only adjectives can occur after this verb (the same is true for seem, appear, smell, and taste).
An even more persuasive bit of evidence for the claim that fun can be an adjective is the fact that it is now also found with the comparative and superlative endings –er and –est, so that can we hear people say this:
There’s nothing funner than those new video games.
This is the funnest thing we’ve ever done together.
Not everyone would use the words funner and funnest. Indeed, after I wrote these sentences, red squiggles immediately appeared underneath them, indicating that my word processing software doesn’t like them either! Nevertheless, it seems that these days the evidence that fun can be used both as a noun and as an adjective is quite convincing.
Are there any other examples of nouns used as adjectives in English? I came across this sentence recently:
We have to be adult about this.
Here the noun adult is used in the sense ‘grown-up’. This is less frequent than fun used as an adjective, but language users are experimenting with new usages all the time, as this passage from the Huffington Post shows:¹
Look at me adulting all over the place. Although I still look to adultier adults (i.e. my husband, who is the adultest) for advice, as I look back on the last almost-decade of my life, I realize I actually have learned a ton of lessons.
The passage is interesting, because its author manages to use adult both as a verb (adulting) and as an adjective (adultier, adultest). There is again a red squiggly objection coming from my word processor to warn me that these examples are unusual. Maybe this guidance is not unreasonable, because most English speakers would regard this as playful language.
The new uses of fun and adult again demonstrate that English is constantly changing, and that some words do not exclusively belong to only one word class over time.
Bas Aarts is Professor of English Linguistics at UCL and the author of Oxford Modern English Grammar. He is a founder of the Englicious website which contains free English language teaching resources and writes the blog Grammarianism for teachers of English.