Cambridge Free English Dictionary and Thesaurus dictionary.cambridge.org
Eu Dictionary http://www.eudict.com/
The EU’s multilingual term base iate.europa.eu
Free Dictionary www.thefreedictionary.com
Merriam Webster on line http://www.merriam-webster.com/dictionary/eu
Oxford Dictionary http://www.oxforddictionaries.com/es
Thesaurus thesaurus.com
Word Reference www.wordreference.com/es/