Wordia is a free visual, video dictionary. Wordia features a selection of user-submitted and professionally created videos explaining the meaning of a word. The videos focus on the everyday use of words while the text accompanying each video provides the dictionary definition of the word. The video below explains the word literacy.

Applications for Education
Wordia is now offering an education section of their service. Wordia Schools provides a private area for students to share videos that they have created for the vocabulary covered in your curriculum. Wordia Schools is free, you can take a tour and sign up here.

Here are some related resources that may be of interest to you:
Visuwords – Online Graphical Dictionary
Lexipedia – Webbed Word Connections
Snappy Words – A Visual Dictionary and Thesaurus