If you are learning Swedish a dictionary is a must. Online or as a book. However I suggest that you also try to get used to a thesaurus. The thesaurus will provide “explanations” by listing a few synonyms in – in this case – Swedish. Sometimes you will find antonyms too. No translations; immersion in Swedish language; a great way to expand the vocabulary.
If you know Swedish already you need one too :). We are never fully educated.
You can use Svenska Akademiens Ordlista – the link takes you to its online Swedish thesaurus. It also comes as a book, of course. With the help of this Swedish thesaurus you also conveniently check spelling, whether it is “en” or “ett“, conjugations of verbs, inflection and declension. And here is the good news – it comes as an app. A free one. Gratis! (means “free”) Grattis! (means “congratulations”). Links at bottom of post. It is far more lighter to carry around in your pocket than the real thing. Promise.
A few pictures to illustrate how it operates.