Hi,
Learning vocabulary out of context is hard. I did however buy 11+ Vocabulary flash cards for my son last year. We used them more like a game, he chose some words and then I would test him on them once he would have learnt them. He also had to try to use them in his work where relevant and had to tell me about it. He was rewarded for doing so. He was always so proud to show off his knowledge

The box we got has 700 cards and we are still using them (will probably see him through his GCSE). They are very good words and we are learning together. It is not only important to know what words mean but how to use them correctly. The cards have examples on them which is great for that.
Hope this helps.