Got Brainy is a site that I've used since it launched a few years ago. Got Brainy features two sections; Brainy Flix and Brainy Pics. Brainy Pics is comprised of images that demonstrate the meaning of a word. Most of the pictures are submitted by students. Brainy Flix is comprised of short videos that illustrate the meaning of words. Just like with Brainy Pics, most of the videos are submitted by students.
Snappy Words is a free visual dictionary and thesaurus. Enter any word or phrase into the Snappy Words search box and it will create a web of related words, phrases, and definitions. Hover your cursor over any word or phrase in the web to read its definition. Click and drag any node to explore other branches of the web. Double click on a node and it will generate new web branches.
Image Dictionary is a Chrome extension that enables users to right-click on a word and quickly find an image that is representative of that word. To use the Image Dictionary extension just highlight a word on a webpage, right-click, and select "image search." The images that are shown come from Wikipedia. Image Dictionary could be a handy little extension to use when you want to quickly find an image to represent a plant, animal, or perhaps a broad topic.
Word Sense is a neat little service that is one part dictionary and one part thesaurus. When you enter a word into Word Sense it will show you the definition(s) for the word as well as the connections to associated and similar words. You can see any of the definitions of the connected words by simply clicking on them to pop-up a definition.
Visuwords uses a web design to show users the definitions of words and the connections between words. To use Visuwords just type a word into the search box and Visuwords will generate a web of related words. Place your cursor over any of the words and the definition appears. Use the color-coded key to understand the connections between the words in any web.