If you’ve been around for a while, you may remember my Draft #4 post from 5 years ago. That post explained why you’re probably using the wrong dictionary and why the correct dictionary is the Webster 1913 + 1828. The dictionary was online but, sadly, has since disappeared. It turned out, though, that you can install the 1913 version locally and make it available through Emacs. It’s really great having it available directly from Emacs and since you have a local copy, there’s no worrying about being online when you want to consult it.
Ever since I installed it, I’ve stopped worrying about its online availability but I’m reliably informed that there are still some people who are not using Emacs and, of course, there’s no reason that they shouldn’t benefit from Webster 1923 too. You can still install it and access it from the command line but many might find that inconvenient.
I just came across this life hacker article on the Webster 1913 dictionary. It affirms that this is the dictionary you want to be using and provides a link to an online version. When I checked my old posts, I discovered that I’d already provided that link but I don’t remember it being a reasonable alternative to the University of Chicago site. Perhaps it was different then or perhaps it’s because it was only the 1913 version. Regardless, it’s the same dictionary you get when you embed it in Emacs so if you’re looking for a great dictionary—see James Somers’ post to find out why it’s the dictionary you should be using—and you’re not an Emacs user, you can consult the online version.