Creating a help/clarification button

Hello, In my survey I have one of the blocks in which I introduce some definitions, which are then used throughout the next questions. However, it is possible that the users might forget those definitions and need some help. Always showing the explanatory text wouldn't be effective cause it takes space, so I was thinking to add some kind of help button (e.g. something which shows like (?) next to the term, and when pressed, it shows the explanatory text). Is there an easy way to do it, or would I have to use javascript? Maybe someone has already implemented it and I don't have to re-invent the wheel? Thanks in advance