English Dictionaries

Monolingual Dictionaries

• Merriam Webster
• Longman Dictionary of Contemporary English

Monolingual and Bilingual Dictionaries

• Wordreference : It is a very useful and complete dictionary. You can choose between several languages and the forum discussions are normally very active and helpful.
• Cambridge: it gives you both the definition in English and the translation in Spanish.
• Oxford Dictionaries
• Collins English Dictionary