Comparison of Dictionaries

I have chosen a word (conceal) and I am going to look for it in several dictionaries. Here you have the results I have got online:

Oxford dictionary: http://www.oxforddictionaries.com/es/definicion/ingles/conceal

Webster dictionary: http://www.merriam-webster.com/dictionary/conceal

Word reference: http://www.wordreference.com/es/translation.asp?tranword=conceal

Webster dictionary for learners: http://www.learnersdictionary.com/definition/conceal

In my opinion Oxford dictionary and Webster dictionary are quite similar but I find it that Webster dictionary is lightly more complete because you have synonyms, antonyms, rhymes and examples without any additional click.  I Think the sentences that are provided in this one  are easier to understand, which is pretty important, otherwise you will need probably to look for another word! The negative point in Webster dictionary is that for listening the pronunciation of the word another tab must be opened (and I couldn’t hear it) whilst you can hear it directly in Oxford dictionary.

The last definition I found belongs to Webster dictionary too, but it is made to English learners,  so there are less resources but they are written in a easier way.