Name of the category is Association and is quite clear. This is new category I have created just for test if the people will like it or not. At this moment some people love this category and others hate it, still it is popular for most of the solvers. Associations are individual so there is no only one correct answer and you have to find the chosen one (expected). You will have a chance to find many hints to help you find the correct answer.
How it works ? I will give you the word FIRE. Association for this word can be WATER. Sometimes you need to find opposite word, sometimes the symbol, meaning or what two words can show together. One more example: Dartagnan .. association can be musketeer , Dumas, book, ..
All improovments of intellect has got the base in free time.