DefineItFast is very useful for me and for my children who are always using the net for their resources in their studies. What I love on DefineItFast is that they have a plugin available for Firefox and Internet Explorer 7 that is installed the browser's built-in search bar. People could also choose their toolbar to install on the computer to have an add-on functionality to right click on the highlighted word on the webpages and select to define it by DefineItFast. I highly recommend DefineItFast for people for word references.