One you’ve got a grasp of Spanish, it’s important to start looking up words in a monolingual Spanish dictionary. Instead of an English translation of the word you’re after, get the definition in Spanish and you have to stretch yourself, suffer, and struggle a bit. But in the end you will learn more if you keep at it.
Sure, you can go out and buy a great printed dictionary, but let’s take a look at the best online monolingual Spanish dictionaries.
The RAE Building in Madrid, Spain.
1. The RAE’s Diccionario de la lengua española.
The RAE publishes one of the most prestigious Spanish dictionaries in print, which is also available on their website. It’s all in Spanish, with Spanish definitions. One of the best free resources you can find online.
I remember when this site was free. Now, if you want to do more than a couple of searches, you’re going to have to sign up and pay for the privilege. But it is probably worthwhile. This dictionary gives you a definition, audio pronunciation, synonyms and antonyms in Spanish, as well as having bilingual diccionarios in Spanish for: English, French, Catalan, German, Italian, and Portuguese. If you want your free trial to last a minute longer so you can really convince yourself to sign up, just clear the cookies in your browser.
3. Signum’s Spanish Thesaurus.
This is a decent dictionary if what you’re looking for is a synonym, antonym, part of speech, or inflection. The only thing missing are some definitions. But hey, it’s free and you can get an idea of what a word means by looking at its synonyms.
4. The Dictionary at ElMundo.es.
This site does not seem as “formal” as the other three– that’s the only way I can describe it– but it has a fairly exhaustive dictionary with definitions, as well as a thesaurus and several bilingual dictionaries. The good thing is it’s free.
Now you have no excuse not to use a monolingual “Spanish-Spanish” dictionary!