MY FAVORITES

https://www.wordgamehelper.com/

(anagrams, words ending with, words starting with, words containing, etc.)

https://inspirassion.com/en/ 

(similar to collocations)

https://languagedrops.com/word/en/english/italian/translate/website/ 

https://languagedrops.com/

(visual dictionary)

https://www.onelook.com/ 

(a lot of dictionaries in one place)

https://www.wordhippo.com/ 

(synonyms, antonyms, rhymes, etc.)

https://www.powerthesaurus.org/ 

(synonyms and antonyms)

https://www.linguee.com/english-spanish

(lots of contextualized examples)

https://www.thesaurus.com/ 

(thesaurus)

https://wordreference.com/ 

(practical dictionary)

https://lingro.com/ 

(make every word on a webpage clickable to translate)

https://www.netlingo.com/ 

(definitions of the internet)

https://www.webopedia.com/ 

(definitions of the web)

http://www.englishdaily626.com/ 

(learn idioms, slangs, etc.)

https://examplum.com/ 

(translations with lots of examples)

https://educalingo.com/en/dic-en 

(synonyms, uses, trends, statistics, word clouds, and much more)

https://www.thefreedictionary.com/ 

(dictionary, thesaurus, medical dictionary, legal dictionary, financial dictionary, acronyms, idioms, encyclopedia, etc.)

https://www.yourdictionary.com/ 

(definition, etymology, sentence examples, etc.)

https://ludwig.guru/ 

(definitions, synonyms, antonyms, and sentence examples)

https://ultralingua.com/ 

(dictionary, conjugations, and numbers)

https://www.etymonline.com/ 

(most popular etymologies dictionary)

https://www.wordsense.eu/ 

(synonyms, word origin, meanings, and multiple languages)

https://www.wordnik.com/ 

(definitions, synonyms, antonyms; not so good, honestly)

https://ozdic.com/ 

(plain dictionary, not so good, honestly)

PRONUNCIATION

https://www.howtopronounce.com/ 

https://forvo.com/ 

MULTILINGUAL

https://www.lexilogos.com/english/index.htm 

https://translated-into.com/ 

https://smodin.io/translate-one-text-into-multiple-languages 

https://www.lexicool.com/ 

https://en.pons.com/translate 

https://www.lingvozone.com/LingvoSoft-Online-English-MultiLingual-Dictionary 

https://www.reverso.net/text-translation 

https://en.bab.la/ 

https://www.diccionarios.com/ 

https://www.online-translator.com/translation 

https://babelnet.org/ 

https://tureng.com/en/spanish-english 

http://www.langtolang.com/ 

https://glosbe.com/ 

https://itranslate.com/translate 

https://www.proz.com/search/ 

LISTS OF DICTIONARIES

https://omniglot.com/links/dictionaries.htm 

https://20000lenguas.com/2016/02/12/30-of-the-best-free-online-dictionaries-and-thesauri/ 

https://en.wikipedia.org/wiki/List_of_online_dictionaries 

https://lingvist.com/blog/best-language-dictionaries/ 

https://wordsburg.com/translate-words-in-different-languages/ 

LISTS OF WORDS

https://en.wikisource.org/wiki/Dictionary_of_spoken_Spanish 

DICTIONARIES THAT I HAVEN'T REALLY USED,

BUT THAT MIGHT BE INTERESTING

(some are apps, add-ons, or extensions)

The dictionaries below are rather confusing. I will keep them here for a while only because they have a few slightly interesting things (but I don't recommend them very much):

https://wordnet.princeton.edu/ 

https://www.logosdictionary.org/ 

https://www.logos.it/ 

http://lookwayup.com/free/dictionary.htm 

https://walrus.lv/abcxxl 

https://about.imtranslator.net/online-services/multilingual-dictionary/ 

http://nyxcore.com/q-multi-language-translator/ 

https://wordweb.info/ 

https://freedict.org/ 

https://italian-english-dictionary-by-vallardi-ios.soft112.com/ 

https://www.ectaco.com/English-Multilanguage-Dictionary/ 

(this one doesn't even seem to work; I might delete it from this list in the future)

RANDOM RELATED SITES

https://grammar.yourdictionary.com/style-and-usage/list-transition-words.html 

https://freelanguage.org/ 

https://eadh.org/projects/interdisciplinary-multilingual-dictionary 

https://www.oxfordlearnersdictionaries.com/us/about/english/pronunciation_english 

https://weglot.com/blog/multilingual-websites-examples/ 

https://buscapalabras.com.ar/ 

POPULAR DICTIONARIES

(I know they are useful, but after 28 years using them (initially on paper version), I find them boring; there are much more interesting resources nowadays out there; still, if you need a “respectable” source, here they are)

https://www.oxfordlearnersdictionaries.com/us/ 

https://www.oxfordlearnersdictionaries.com 

https://dictionary.cambridge.org/ 

https://www.merriam-webster.com/ 

https://www.macmillandictionary.com/us/dictionary/american/ 

https://www.collinsdictionary.com/dictionary/english 

https://en.langenscheidt.com/ 

https://www.ldoceonline.com/ 

https://www.larousse.fr/dictionnaires/francais