What is the definition of "acquaint"? Most people will respond with a definition like "Well, if you acquaint someone with someone else..." or "If you are acquainted with someone...", because acquaint is never used as a normal verb, it's always got the preposition "with".

We call these verb-plus-preposition phrases "phrasal verbs", and they often get a lesson or two to themselves in many English Language courses. Unlike "acquaint", most phrasal verbs have productive verbs as their base, e.g. "stop" is used on its own but also is found in phrasal verbs like "stop over".

That means that, unlike acquaint, both "stop" and "stop over" have senses of their own and therefore their own entries on Cambridge Dictionaries Online. But with "acquaint", we have a problem. If someone looks up "acquaint", we want them to find the phrasal verb (preferably first). We want them not to find the headword. But we still want the user to be able to get information about "acquaint" - chiefly the pronunciation.

1. Create an entry for "acquaint" but give it no definition but maybe a cross-reference to "acquaint sb with sb". But users will still find "acquaint" first, which is not helpful.
2. Create an entry for "acquaint" and make up a definition for "acquaint", even though no-one uses it. But this goes against our aim to teach English as it is actually used, and it blurs the line between verb and phrasal verb which teachers work hard to explain.
3. Do not create an entry for "acquaint", and only have an entry for "acquaint sb with sb". We lose the pronunciation of "acquaint"
4. Put phrasal verbs in together with the verb, so users find the verb and all phrasal verbs. The downside of this is that we end up with very, very long entries for verbs like "set" and "get".

We have used option 1 in our CD-ROM dictionaries; it can work there as the phrasal verb is always displayed after the verb. For the website and especially the API, that feature doesn't apply.

Many online dictionaries go for option 2, making a definition for the word as if it ever existed on its own. But this is not really meaningful: we don't define "capella", we define "a cappella" (unless we're writing an Italian dictionary where "capella" means chapel).

We've tried out option 4, and it can work for smaller dictionaries, but it makes some verbs in larger dictionaries very hard to use, so in the end, we picked the third option as the most user-friendly.

However, rather than losing out on the info for acquaint, in our Learner's Dictionary, we added the information of the main verb in the 'subheading' below the phrasal verb - see what you think. We're planning to standardise this style for all our datasets shortly. In the API XML, this is the anc element.

NB: If you look very carefully, there is also an idiom problem, as there are two words in the Advanced Learner's Dictionary which are only defined as idioms: hots and Rome, and there are also several others for which, as a particular part of speech, the only use is as an idiom.