30 of the best free online dictionaries and thesauri

This is the first time we are proposing a list of 30 free online dictionaries and thesauri exclusively in English. We have already presented different posts about linguistic tools, such as glossaries and international dictionaries. We hope you find it useful, and welcome any suggestions for improvement or contributions for future linguistic posts. So please have a seat:

  1. Merriam-Webster Visual Dictionary online: an interactive dictionary with an innovative approach which helps you learn English in a visual and accessible way. From the image to the word and its definition, the Visual Dictionary Online is an all-in-one reference. Perfect for home, school or work.
  2. Merriam-Webster Dictionary and Thesauri: you should know this famous English dictionary full of information, definitions, etymologies, phonetics, pronunciations, translation, and so much other.
  3. Urban Dictionary: an online slang dictionary which contains many non-explicit definitions. You can find it in several languages such as Spanish, Bengali, Polish, Serbian, Chinese and so on.
  4. Wordreference.com: is an dictionary with 17 different languages and a good quantity of combinations. It is called the holy grail of free online language dictionaries. It has also forums where you can ask your doubts and questions.
  5. Your dictionary: a dictionary and thesaurus with so many language examples, references, articles, resources, linguistics tools such as a world finder for Scrabble, grammar among other interesting materials.
  6. Dictionary.com: definitions, daily crosswords, word games, synonyms, translations, blog and so much more. Includes definitions from American Heritage, Random House, and Merriam-Webster.
  7. Macmillan Dictionary: one of the world’s leading reference publishers which is an essential reference for the classroom and home. You can find both British English and American English dictionaries and lots of other linguistic free tools.
  8. Cambridge Dictionaries: is it among one of the most popular English dictionaries. Different corpus-informed dictionaries for English language learners at all levels. They’re ideal for anyone preparing for Cambridge English exams and IELTS.
  9. Definitions.net: is a free multilingual dictionary that provides instant definitions from many respected reference resources. The definitions come with usage examples, part of speech, etymologies, phonetic and voice pronunciations, citations and translations to more than 40 different languages.
  10. Oxford dictionaries: a dictionary with more than 150 years of story. Defining words, collection, process, and analyse the living language and how it’s changing, its history, its usage, its relations with other languages, and who’s using it, from highbrow to slang.
  11. Thesaurus.com: it is words grouped together according to similarity of meaning containing synonyms and sometimes antonyms.
  12. The Free Dictionary: you can find a dictionary, thesaurus, medical ditionary, legal dictionary, financial dictionary acronyms, idioms, encyclopedia, an English language forum and so much more. It is also available as an app for iOs and Android.
  13. Wordnik.com: English dictionary and language resource that provides dictionary and thesaurus content, some of it based on print dictionaries such as the Century Dictionary, the American Heritage Dictionary, WordNet, and GCIDE. Wordnik has collected a corpus of billions of words which it uses to display example sentences, allowing it to provide information on a much larger set of words than a typical dictionary.
  14. Visual Thesaurus: an interactive dictionary and thesaurus which creates word maps that blossom with meanings and branch to related words.
  15. One Look: Meta-search tool indexing more than 19 million words from 1,000 online dictionaries. It also has a reverse dictionaryand translations.
  16. Netlingo: an online dictionary of thousands of computer and Internet terms, online slang and more than 3000 terms to check.
  17. Webopedia: an online tech dictionary for IT professionals, educators and students. the tool provides definitions to words, phrases and abbreviations related to computing and information technology.
  18. Computer Language: a dictionary, a glossary, IT and consumer electronics definitions with more than 30,000 entries. available for PCs, iPhones and Androids.
  19. Answers: an aggregator of definitions, encyclopedia entries, and language translations. The site supports English, French, Italian, German, Spanish, and Tagalog.
  20. Med Terms: online medical dictionary that provides quick access to hard-to-spell and often misspelled medical definitions through an extensive alphabetical listing. It is the medical reference for MedicineNet.com. prepared by doctors who define difficult medical language in easy-to-understand explanations of over 16,000 medical terms.
  21. Medi Lexicon: a medical dictionary that contains definitions of thousands of medical terms from Stedman’s comprehensive medical lexicon. The dictionary has over 200,000 medical, biotech, pharmaceutical and healthcare acronyms and abbreviations.
  22. WebMD Medical Dictionary: find definitions for thousands of medical terms, treatments, and tests — even health-related abbreviations, prefixes, and suffixes.
  23. Law Dictionary: a dictionary that is designed and compiled to give information about terms used in the field of law. Concise, easy-to-read definitions from The People’s Law Dictionary. In addition, there is an app available for use on iPad and iPhone.
  24. Investor words: it is an onlined financial glossary which contains over 15,000 definitions, assisting millions of individuals comprehend valuable concepts needed to succeed in today’s financial world. The glossary for InvestWords is updated regularly and covers important topics like stocks, bonds, banking, accounting, insurance, and Forex. They also offer the InvestorWords Term of the Day newsletter, usable tips and Q&A resources that visitors are able to access.
  25. Marketing power Dictionary: marketing definitions, the meaning and explanation of obscure phrases, marketing terms with more than 4,000 cross-referenced definitions.
  26. Wolfram MathWorld: is the web’s most extensive mathematical resource, provided as a free service to the world’s mathematics and internet communities as part of a commitment to education and educational outreach by Wolfram Research, makers of Mathematica.
  27. Acronym Finder: abbreviations, acronyms and initialisms dictionary with more than 1,000,000 human-edited definitions. There are different categpries such as information technology, science and medicine, slang and pop culture, business and finance, organizations and schools, military and government, etc.
  28. Abbreviations: the world’s largest and most comprehensive directory and search engine for acronyms, abbreviations and initialisms on the Internet. Abbreviations.com holds hundreds of thousands of entries organized by a large variety of categories from computing and the Web to governmental, medicine and business and it is maintained and expanded by a large community of passionate editors.
  29. Biology Online Dictionary: an open dictionary with over 60,000 biology terms. It uses the wiki concept, so that anyone can make a contribution. The site provides a wealth of information in the diverse field of biology offering a forum for discussion, an editable-dictionary with thousands of terms, links to external resources, tutorials, articles and a biology book catalogue with user reviews.
  30. The Science Dictionary: a specialized science search engine that queries billions of the web’s top science pages for scientific information. This dictionary has been featured as a trusted resource by numerous educational institutes (K-12 and higher education) in the United States, the United Kingdom, and Canada. Researchers, students, and professionals around the world use The Science Dictionary as their goto website for finding relevant scientific information.

Online linguistic tools and dictionaries for transaltion

There are more than 30 wonderful dictionaries but this is our proposal. We hope you will enjoy it and find it useful for your professional work and studies. Should you have any other proposal to share with us please do not hesitate to write and let us know. We are glad to contribute our ideas and expertise to help you. We hope to see you soon following and reading my blog. Have a nice day!


26 respuestas a «30 of the best free online dictionaries and thesauri»

  1. Avatar de Yigal Ben Efraim

    Thanks for including Abbreviations.com & Definitions.net!

    1. Avatar de @OlgaJeno

      Dear Yigal,

      thank you for your time and for having read the article. You’re always welcome to the blog. Fee free to comment and write us whenever you want. It’s a pleasure!

      All the best,

    2. Avatar de abegbesilgmail

      Thanks. It would be very useful in any technical translation.

      1. Avatar de @OlgaJeno

        You’re welcome!

        Have a nice day,
        Olga 🙂

      2. Avatar de Gloria Martínez Nieto

        I like this a lot, Thanks you.

  2. Avatar de Lluís Barberà i Guillem

    Buenos días,

    Desearía saber si, de la misma manera que hay un «Linguee» y un «Reverso», como mínimo, como recursos con posibilidad de traducción al castellano desde el inglés (llengua que actualmente traduzco) y con frases que sirven de ejemplos bastante interesantes, hay también en catalán.

    Actualment llevo la web http://malandia.cat, la cual empecé traduciendo canciones, entre enero y septiembre de año pasado con traducciones del catalán popular del País Valenciano (lo que aquí llamamos «valencià») al inglés, con la revisión de un maestro irlandés.

    Pero desde octubre empecé a hacer traducciones de temas diversos del inglés al catalán y, en estos momentos, estoy en contacto con una maestra britànica (Dany Rosevear) que tiene una web con muchísimas canciones infantiles (con una cantidad interesante de traducciones del neerlandés, del polaco, del francés, del catalán y de algunas de la web que gestiono).



    1. Avatar de @OlgaJeno

      Hola Lluís:

      Gracias por escribir en el blog y compartir tus dudas. Como excelente herramienta de catalán disponible en línea te recomiendo la web del Termcat, centro de terminología catalana llevado por el IEC (Institut d’Estudis Catalans). Es una herramienta con varias combinaciones lingüísticas. La web es: http://www.termcat.cat

      Si necesitas más recursos no dudes en escribirme para que te pueda ayudar. Ánimos con tu trabajo. Saludos,

  3. […] lenguas hat im Artikel „30 of the best free online dictionaries and thesauri“ nützliche englischsprachige Online-Lexika gesammelt (via ICT-Unterrichtsideen auf scoop.it […]

  4. Avatar de Gloria Martínez Nieto
    Gloria Martínez Nieto

    Me gustarí saber si hay un diccionario juridíco de español-inglés e inglés español, como el Linguee

    1. Avatar de @OlgaJeno

      ¡Hola Gloria!

      Te dejo algunos enlaces de interés:

      – Encyclopedia of Law & Economics : http://encyclo.findlaw.com/index.html

      – Office of Public Sector Information: http://www.opsi.gov.uk/

      – British and Irish Legal Information Institute: http://www.bailii.org/

      Espero que te sirvan. Saludos,

  5. Avatar de Jill

    Blueseal dictionary: http://dict.blueseal.eu

    Dictionary for German, Spanish, English and French plus synonyms.

    1. Avatar de @OlgaJeno

      Many thanks Jill for this dictionary! I will add it to the next list.

      All the best,

    2. Avatar de @OlgaJeno

      Many thanks for the dictionary Jill!


  6. […] Selección de diccionarios de inglés por Olga JeNo […]

  7. Avatar de Fabio Descalzi

    This list is a must-read! Included it in my list-of-lists! 🙂

    1. Avatar de @OlgaJeno

      Let’s go! Enjoy the reading and thank you for sharing it! 🙂

  8. Avatar de misshelenweb

    Useful list of dictionaries. I will recommend it to my pupils! 👍☺

    1. Avatar de @OlgaJeno

      Lovely! I’m glad they are useful for you and your students!

      Cheers from Luxembourg!

    1. Avatar de @OlgaJeno

      ¡Qué bien que te guste Yoya!

      Saludos y buen trabajo,
      Olga 🙂

  9. […] Il s’agit là d’une sélection, et si tu en connais d’autres viens donc les partager avec la communauté CourseFinders.com sur Facebook et Twitter! Une liste plus complète peut d’ailleurs être trouvée sur l’excellent article de blog suivant : https://20000lenguas.com/2016/02/12/30-of-the-best-free-online-dictionaries-and-thesauri/ […]

  10. Avatar de Amanda Isabel González
    Amanda Isabel González

    Increíble glosario de diccionarios online…me parece una magnífica herramienta para accesar de manera inmediata a los diccionarios a través de esta página…mil gracias…me encanta este blog…felicidades!!! Soy de México…

    1. Avatar de Olga Jeczmyk

      Hola, Amanda:

      muchas gracias por tu mensaje y por tan buena acogida del blog. Me alegro mucho que el blog te parezca útil y que puedas aprovechar las herramientas que se van publicando periódicamente.


  11. Avatar de Danielthope

    Hardly joined. I’m Individual. Lately wanted to chance hello!

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