Use more than one dictionary.
The first thing everyone needs to know is that you don't have to stick to just one dictionary. You can and should consult multiple dictionaries. In fact, there are multi-dictionary websites to help make this easy, for example:
There are a lot of great dictionaries out there, but none of them is perfect. If you check your favorite dictionary, and you still don't understand, try another dictionary.
Prefer learner's dictionaries.
It also helps to know about the two main kinds of English dictionaries:
- Dictionaries written for native speakers.
- Dictionaries written for learners (learner's dictionaries).
Both have their pros and cons, but we should try to favor learner's dictionaries here on ELL. Dictionaries written for learners often have a number of really important features:
- Definitions written mainly using a smaller vocabulary, so learners don't have to look up another word to understand the definition.
- Frequency information, so learners can prioritize the words they really need to learn.
- Entries arranged in order of most important to least, rather than in (for example) historical order.
- Pronunciation in both AmE and BrE given with IPA transcriptions, not respelling schemes.
- Easy-to-understand example sentences.
The exact set of features depends on the individual dictionary. A lot of this came out of research done by publishers like Longman, who were interested in how learners use dictionaries and wanted to make dictionaries that met their needs.
Examples of good learner's dictionaries:
But don't ignore dictionaries written for native speakers.
Dictionaries written for native speakers can have their own advantages:
- Broader coverage: more words, or more meanings for the same words.
- Historical information: Some dictionaries focus on the history of words, but learner's dictionaries rarely do.
- More examples: the largest non-learner's dictionaries right now have more example sentences than learner's dictionaries.
So although I'd focus on learner's dictionaries, I wouldn't ignore dictionaries written for native speakers, either. Just remember to check multiple dictionaries and look for whatever is most useful in a particular case.
Examples of good dictionaries not specifically written for learners:
Also consider specialized dictionaries.
Besides general-purpose dictionaries, there are also entire dictionaries dedicated to other topics. The main three pronunciation dictionaries are:
When writing an answer, please focus on IPA. Dictionaries written for native speakers of American English often use pronunciation respelling schemes, which might seem easier at first glance, but these transcriptions are unfortunately not as useful for learners.
There are also entire dictionaries for collocations, phrasal verbs, idioms, and so on, as well as dictionaries devoted to specific topics such as business English or law. Any of these can be useful in the right context.
You may have favorite dictionaries – I certainly do! – but keep your mind open and check multiple dictionaries frequently. You might be surprised when, after checking six or seven dictionaries, you finally happen upon one with the perfect definition for your answer.
But don't link to a Google search.
Sometimes answers contain links to Google searches instead of links to actual dictionaries. However, this is a bad idea for a number of reasons. The most important one is that Google doesn't show definitions to all users, so the people clicking your link might not see a definition. For that reason alone, we should avoid these links.
If you like the definition on Google search, please link directly to the Oxford Dictionaries website, which is where the definitions come from originally. For more information, please see this meta discussion: Is Google Dictionary a valid definition reference (in particular in answers)?