Macmillan's Open Dictionary provides quality definitions for new words
When I first wrote about the Urban Dictionary, many people were quick to note that they already know the service. The Urban Dictionary may be well-known, but it is hard to say that it is well-regarded. True, it is "democratic." You can vote poor definitions down -- but it's not exactly a paragon of linguistic quality, though.
Its premise seems similar to that of the Urban Dictionary; readers suggest definitions and Macmillan features those definitions on the site. However, there are a couple of notable differences between Macmillan's Open Dictionary and the Urban Dictionary. One such difference is that, while The Urban Dictionary seems to be a hodgepodge of definitions, Macmillan's Open Dictionary is more of a curated resource, composed of carefully handpicked definitions. In my stroll through the site, I could not come across any definitions that seemed badly worded or otherwise lame.
The flipside of this approach is that you cannot vote definitions up or down, and the selection is tiny compared to the Urban Dictionary. Also, not every definition gets featured, I imagine. Still, when a definition does get featured, I can be pretty certain that it is of high quality (and has, perhaps, been edited by Macmillan as well). So, this is more about quality than about democracy or "being social."
Another key difference is that the Open Dictionary does not feature only slang; it's got all sorts of "new words", or neologisms. In the future, when I need to find a definition for a buzzword that I don't know, I will probably try the Open Dictionary before I try the Urban Dictionary.