Today’s column is prompted by some recent teacher comments, to the effect that students often find it hard to distinguish between adjectives and verbs. To this, we say don’t worry - it’s perfectly normal. In fact, as grammarians, we should probably let you into a little secret: it’s genuinely not always easy to tell, as there is a particular group of words that can be both!

For convenience, we will call these ambiguous forms participials, since they are words where the adjective is essentially identical to the present and past participle forms of verbs. In other words, they are cases where the adjective looks identical to a verb ending in “ing”, “ed”, and “en”.

Classic examples of such forms are “broken”, “entertained”/“entertaining”, “frightened”/“frightening”, “intimidated”/”intimidating”, and “married”.

With this ambiguity in mind, consider the following sentences:

(1) We will be entertaining friends tonight

(2) The moment I heard Chomsky I was taken to a CIA black site

(3) They were married by Kermit

Each of the words in bold here is unambiguously a verb. But it’s actually pretty easy to construct alternatives where the same words are ambiguous between verb and adjective:

(4) We will be entertaining tonight

(5) The moment I heard Chomsky I was taken

(6) They were married

As written, each of these forms can now be construed as either an adjective or a verb. It all depends on how you read them.

Grammar advice

In the adjective version, a property is applied to the subject of the sentence; in the verb version, the word specifies the action performed.

Thus, reading “entertaining” as the adjective, (4) states just how naturally fabulous we plan to be; reading it as the verb, however, (4) simply notes that we are having some people round for dinner.

But if there are such ambiguous forms, how can you always know for sure that a form is a verb or an adjective?

Well, as any honest grammarian will tell you, you can’t: ambiguity is just part of the language, something you get used to over time.

In that sense, we all need to accept that such ambiguities are inevitable, and that it really can be OK to read a sequence in more than one way. In fact, being able to recognise this kind of ambiguity is a key marker of actually understanding what’s going on.

Verbs and adjectives

Still, it is handy to be able to recognise both when a sequence is ambiguous and when it’s not. And here, all is not lost, because we grammarians have a few tricks up our sleeves. Moreover, since there’s no grammarian equivalent of the Magic Circle, we can happily reveal these tricks without fear of expulsion. The first rule of grammar club is, after all, that it’s fine to talk about the rules of grammar club.

So here’s how we do it, and you can, too:

[A] Modification by “too” and “very”

A very simple test is whether or not the word is modified by the adverbs “too” or “very”. If it is, it’s an adjective.

Conversely, this is one reason we know (4) and (5) are ambiguous, since each has two readings, one where we can add “too” or “very”, and one where we can’t:

(4a) We will be very entertaining tonight (entertaining=adjective)

(4b) We will be entertaining tonight (entertaining=verb)

It’s also how we know for sure that the forms in (1) and (2) are unambiguously verbs, since Standard English doesn’t let us add a “very” to these sentences (at least, not yet!)

(2) The moment I heard Chomsky I was taken to a CIA black site (taken=verb - not possible to modify “taken” with “very”)

[B] Noun phrase as object

Verbs can take noun phrases as direct objects, adjectives generally can’t. Again, this helps us recognise “entertaining” in (1) as clearly a verb because it has the noun phrase “friends” as object:

(1) We will be entertaining friends tonight (entertaining=verb)

It is also how we know (4) is ambiguous, since on the verb reading we can add a noun phrase, but on the adjective reading we cannot:

(4a) We will be (very) entertaining tonight (adjective, noun phrase object not possible)

(4b) We will be entertaining (friends) tonight (verb, noun phrase object possible)

[C] Stick in a copular verb

English makes available a number of verbs that accept adjectives as complements but not verbs. Two useful examples of such verbs are “seem” and “look”. This means that if you can replace the verb that introduces the participial form with either “seem” or “look”, then the participial form is an adjective; if you can’t, it’s a verb. This is how we know “married” is a verb in (2), since we cannot replace “were” with either “looked” or “seemed”:

(3) They were married by Kermit (verb, not possible to stick in “seemed”/“looked”)

And it’s also how we know (6) is ambiguous, since we can give it two readings, one where we can replace the form with one of these verbs, and one where we can’t:

(6a) They were married (adjective form, can stick in “seemed”/“looked”)

(6a) They were married (by Kermit) (verb form, can’t stick in “seemed”/“looked”)

Ian Cushing teaches English linguistics at University College London and is a doctoral researcher in applied linguistics at Aston University, working on grammar teaching at secondary school level. Mark Brenchley is an associate research fellow at the Centre for Research in Writing at the University of Exeter. He works on the Growth in Grammar project, which is seeking to understand what grammatical development in student writing actually looks like.