I recommend using a monolingual dictionary (this means word definitions are given in English only) designed for learners of English. Apart from the definition of words you will also find a lot of background information on grammar, collocations (words which often appear together) and common errors etc.
So here are my top five dictionaries!
If you are looking for a definition of an idiom, I recommend using a monolingual dictionary as well. Because idioms cannot be translated literally. Therefore, to fully understand the meaning of an idiom (and how it’s used in context!) it’s best to consult a monolingual dictionary.
Once you know the meaning of a word and you are interested in how it is actually used in everyday English I recommend a collocations dictionary:
At the end of the day, it’s a matter of preference which dictionary you like best. This list is not exhaustive; the above mentioned dictionaries are my favourites.
Which dictionary do you like best? Do you use any others than the ones mentioned? Leave me a comment below!