“voluntary exchange” or “voluntary market exchange”
I have one request.
Scott Vonasek

Free market and capitalism have nothing to do with each other. Free markets are cool, and used as an excuse for capitalism by conflating the two terms. 
You have capitalism without free markets e.g. in the Chinese Energy sector, and you had free markets without capitalism e.g. in pre-civil war Catalonia.
Capitalsim indicates that there is a seperate class of people who only own means of production and do nothing else. Free market means that every good can be made and sold by anyone. No correlation there, and not to be conflated.