Priberam Informática is an irreplaceable online resource for the Portuguese language
You may have noticed there aren’t a lot of traditional resources such as expansive, accurate dictionaries and grammar reference. Though this can be frustrating perhaps to the beginning student, once you know your way around the language a bit (i.e. are able to read resources that themselves are in Portuguese) a whole world opens up. At the absolute top of the list of such Portuguese-language resources is Priberam.
An online Portuguese-to-Portuguese dictionary, grammar reference and even a correction function(!), Priberam is really like nothing else out there on the web.
Consider bookmarking it or saving it with del.icio.us for frequent use. Your Portuguese will improve as a result.
There are days when I literally have Priberam open all day. Some of my Brazilian friends like to (I think perhaps intentionally) use long, poetic words that I have never heard before. For this and many other situations, Priberam is a trusty companion. Check it out.