How to learn new words permanently?

Context is your best teacher here. Forget the ineffective, boring and tedious word-by-word and out-of-context memorization techniques, they simply do not work. Instead, use the language as much as you can and in as many different, creative and challenging ways as possible. Read, write, speak, listen, understand, communicate. Choose material that is neither too easy nor too difficult for your current skills, but which you find motivating and interesting.

Also, buy yourself a single-language dictionary which explains the words so that you can understand them better.