How I Use It
I would use this with students to build vocabulary during a unit. What works about this tool is that there is quite a bit of flexibility for the learner in getting more information about a word, if needed. The color coding of the parts of speech is great, as is the pronunciation option and it's predictive text for searching. This is a paid service, though, so depending on the number of users, it could be pretty costly.
As a vocabulary builder, this could be very useful, especially for students who are second language learners or those who might struggle with vocabulary. What would make this more powerful would be the ability to embed, like on a blog or website so that students could get limited access to certain words (and the chance to experiment). Also, while it's a paid service, more transparency about the pricing structure would make it more attractive.