I think the idea is awesome, but add options to import pre-made vocabulary lists. If you're wanting to learn new words, I think it would make sense for you to start seeing lots of them. Then also a option to view the definition by selecting a word.
this is really superb addon but there are some problems. 1. after adding more words i'm not able to scroll down to see the last words i added.. 2. please add an option to export the words i add with meanings if possible or sync options across browsers..