I don't really think that it's useful and productive to memorize just separate words especially in a short time. If you really need to memorize something then try to learn whole phrases and word combinations)

What do you mean by a "short time"? How many words? What themes? Why the rush? Otherwise, there is no way, in my experience, of learning words other than by repetition and use. There is some useful information on Italki: http://www.italki.com/articles/english