Recently I posted an article about Google’s dictionary (titled: Did you know Google has a dictionary?) that was quite popular. To add to your dictionary collection, I encourage you take a look at another online dictionary, called Definir.
Definr.com is a fast, free dictionary based on Princeton’s open WordNet 2.0.
The website framework is Ruby on Rails. Looking up words in a dictionary is easy, so we do that with MySQL and cache the top 10,000 definitions in memory.
Doing word completion (a.k.a. auto-complete, auto-suggest, globbing) is not easy, at least not when you have to search through 200,000 words for every keystroke. So our word completion is done in a C module for Ruby, and the word completion server is separate from the rest of the site.
With the DefinrBot algorithm, we can do 190,000 word completions per second without caching, and that translates to about 10,000 completions per second once the Ruby layer is factored in.
Definir is available as a Firefox extension or you can drag Definir to your Firefox toolbar, where you can look up words on the fly. I tested the toolbar bookmarklet in Google Chrome, and it worked there, as well.