Everyone agrees that phrasal verbs are an integral part of the English language, but does anyone agree on what a phrasal verb actually is? Well, I’m happy to say that Liz Walter (my co-author on Phrasal Verbs for Natural English) and I are in broad agreement, but you may have other ideas…

The first characteristic of a phrasal verb is fairly obviously that it has two parts – a verb followed by a particle, or, less commonly, three parts – a verb followed by two particles. No controversy there.  So let’s look at a typical phrasal verb – ‘let someone down’ (= disappoint someone by not doing what you’ve agreed). Well, the other obvious characteristic of this unit is that the meaning of the combined verb and particle are unquestionably different from the meaning of those words when separate. (No learner of English could be expected to guess the meaning if ‘let down’ was presented out of context.)

But does that mean that all phrasal verbs have an idiomatic element to them? Well, no, not if you consider ‘get on’ to be a phrasal verb, as in ‘I got on the bus.’ – which I’m supposing you do. (And certainly all the dictionaries I have on my desk here treat it as such.) After all, both verb and particle in ‘get on’ convey core meanings of both ‘get’ and ‘on’. So why is ‘get on’, as opposed to any commonly co-occurring verb + particle combination, a semantic unit in its own right? It must be because ‘get on’ is pretty much exclusively how we describe that particular action. (How else would you say it in normal English?)  So there’s another criterion for defining what a phrasal verb is: a verb + particle combination that is far and away the most common way of referring to a particular action.

But if we go with this second criterion, how do we feel about ‘fall off’, as in ‘to quickly move from a higher position to a lower one, usually as a result of an accident’? Semantically, it is only the sum of its parts, (and therefore not very phrasal verb-y) but isn’t it what we say to describe, for example, what happens to an item on a shelf that gets knocked? Shouldn’t it therefore be in dictionaries, flagged up as a phrasal verb. (It isn’t.)

And when does a verb+particle combination become a bona fide phrasal verb? On the radio last week, a victim of domestic abuse gave a testimony of her experiences. To preserve her anonymity, explained the presenter, her words had been ‘voiced up’. Should I have made a note of that combination? Was it a newly minted phrasal verb that I’ll be hearing all the time, or just a creative, one-off combination?

Phrasal verbs, in this regard, are a bit like idioms. There are typical examples that demonstrate all the classic characteristics and we all recognise them for what they are. But around this central core of clear-cut phrasal verbs, there are a whole lot of grey areas.