Oxford Advanced Learner's Dictionary

That's really good! The Oxford Advanced Learner's Dictionary is online. This is my favourite dictionary. It's a monolingual dictionary, so all explanations are in English. It's therefore not a dictionary for people who are starting to learn English,

but for more advanced students it can be of great help.

Here is the link to the homepage of the dictionary:

http://oald8.oxfordlearnersdictionaries.com/

And here is the link  to the part of the dictionary where you can find a picture that will help you understand the meaning of the word: http://oald8.oxfordlearnersdictionaries.com/images/

Example:

Brussels sprout:

And if you then click on the picture you get this: