Visuwords is an online tool that provides more than just the definition of a word.
You can simply search for a word, as you normally do in a dictionary. Visuwords doesn't just show a definition, but also shows relations with other words and visualises this using colours and different types of lines.
Example of an assignment using Visuwords:
Read the text and write down all the words that are unfamiliar to you. Enter these words in Visuwords. Can you derive the definitions from the surrounding words displayed in Visuwords?