When I worked with the last blog post where I wrote about news, we were also supposed to test different online dictionaries. I tested some of the dictionaries from this link http://www.eoioviedo.org/webteca/recursos%20ingles/dictionaries.htm . I only tested the dictionaries who was English- English. Here are the dictionaries I tried out and what I thought about them.
http://www.onelook.com - This dictionary was not the one I liked the most. When I searched for a word I got suggestions on other different online dictionaries I could use, which I thought would take more time than using one of the others where I could just get the meaning of the word immediately.
http://nhd.heinle.com/home.aspx - This was one of the dictionaries I like most. When I searched for a word I got the meaning of the word immediately, and in addition to this there was some examples of how I could use the word in sentences.
http://thesaurus.reference.com - This was the dictionary I liked least. When I searched for a word I did not get a very good description or meaning of the word, and I think the whole layout was a bit messy.
http://www.thefreedictionary.com/ - I thought this dictionary was quite good. If I searched for a word I got the main meaning of the word with three options or explanaitions of the word. Then if I scrolled down at the page, there were more suggestions of what the word could mean. So this dictionary was also very good.
The dictionary I would prefer is this http://nhd.heinle.com/home.aspx - it is very clear and easy to use, and you get good explanations.