I am a terrible speller. So when spell check is not available I turn to Google for dictionary options to ensure I am spelling correctly. I recently found a simple and fast alternative called definr. Definr, just as it may sound, is an online dictionary.
Built on the Ruby on Rails framework, Definr is a fast, free dictionary based on Princeton's open WordNet 2.0. When you enter a word, definr starts to auto-complete word options as you type. Upon selecting a word definr brings back the dictionary results very quickly. Definr is all about performance and cache the top 10,000 definitions in memory so they can bring results more quickly - see some of the stats for yourself. Additionally, you can check out the top 50 words.
Definr focuses creating a simple and incredibly fast dictionary and delivers on its mission. Definr also offers a Firefox browser extension, bookmarklet and some other tools which enables users to search for words directly from the Web browser saving more time. So the next time you looking for a word you might want to check out definr for a quick fix.