One very quick way to look up words on Google is simply to type define:anyword in the Google search field. However, their actual dictionary is far and away my favourite of all the dictionaries I've reviewed, mainly because of its clean, ad-free format. When you click on a sound icon to hear a word pronounced, it doesn't open in another annoying window. The definitions are not too complicated for use by school kids and there are examples used in context and links to other definitions found on the web. At any time, at the top of the page, you can also access web-links, images, videos, etc. that are part of a regular Google search. The site also works with NaturalReader.
Look up words in the Visuwords online graphical dictionary and thesaurus to find their meanings and associations with other words and concepts. Produce diagrams reminiscent of a neural net. Learn how words associate.
Very cool Firefox extension lets you select a word and perform a multitude of actions including reference to dictionaries or wikipedia, convert, translate, shop, share, etc. Check out the popular Firefox Add-On Hyperwords.Updated to version 5.5 and now supports Twitter and Facebook. Available for free from http://www.hyperwords.n...
Ray Kurzweil has designed a free screenreader with text-to-speech, tracking, highlighting, note-taking and lots of books for free or purchase. I am investigating whether it's possible to convert .pdfs and .doc files into the format it uses. PRCVI is investigating this reader as an alternative for students who don't have Kurzweil.
Enter a word to look up or just explore by theme. The definitions are constructed as pages with a small amount of text and labeled drawings on which the labels are also clickable links. This would be a great "multiple means of representation" resource.
Online thesaurus that displays word associations in a colorful web. The thesaurus gives you an option to change the display, viewing all or just the synonyms, antonyms, fuzznyms, adverbs, adjectives, verbs, nouns. In that respect, it's a lot less visually confusing than Visuwords.